title: Anchorage, Alaska

text: The Anchorage Community Survey, a public survey conducted in 2004–05 by the Justice Center at University of Alaska Anchorage, found that overall, Anchorage residents are fairly satisfied with the performance of the Anchorage Police Department. Most survey respondents perceived the justice system to be "somewhat effective" or "very effective" at apprehending and prosecuting criminal suspects, bringing about just outcomes, and reducing crime.


title: Anchorage, Alaska

text: Public education in all of Anchorage municipality, including Eagle River, Chugiak, Fort Richardson and Elmendorf Air Force Base, is managed by the Anchorage School District, the 87th largest district in the United States, with nearly 50,000 students attending 98 schools. There are also a number of choices in private education, including both religious and non-denominational schools.


title: Anchorage, Alaska

text: Anchorage has four higher-education facilities that offer bachelor's or master's degrees: the University of Alaska Anchorage, Alaska Pacific University, Charter College, and the Anchorage campus of Texas-based Wayland Baptist University. The University of Alaska Fairbanks also has a small Center for Distance Education downtown. Other continuing education facilities in Anchorage include the Grainger Leadership Institute, Nine Star Enterprises, CLE International, Nana Worksafe, and PackBear DBA Barr & Co.


title: Anchorage, Alaska

text: Ninety percent of Anchorage's adults have high-school diplomas, 65 percent have attended one to three years of college, and 17 percent hold advanced degrees.


title: Anchorage, Alaska

text: Anchorage has the most ethnically diverse schools in the United States, including the three most diverse high schools, the three most diverse middle schools, and the 19 most diverse elementary schools. Even the least diverse schools in Anchorage rank in the top 1% nationally.


title: Anchorage, Alaska

text: The Chugach School District operates neighborhood schools in Valdez–Cordova Census Area, Alaska, as well as the supplementary Voyage to Excellence Residential School in Anchorage; its board office is in Anchorage. The Aleutian Region School District, which operates schools in areas of the Aleutian Islands, has its district administrative offices in Anchorage.


title: Anchorage, Alaska

text: Anchorage's leading newspaper is the "Anchorage Daily News", a citywide daily newspaper. Other newspapers include the "Alaska Star", serving primarily Chugiak and Eagle River, the "Anchorage Press", a free weekly covering mainly cultural topics, and "The Northern Light", the student newspaper of the University of Alaska Anchorage. Anchorage's major network television affiliates are KTUU 2 (NBC), KTBY 4 (Fox), KAUU 5 (CBS/MyNetworkTV), KAKM 7 (PBS), KTVA 11 (Rewind TV), KYUR 13 (ABC/CW), and KDMD 33 (Ion/Telemundo/MeTV). Anchorage is one hour behind the Pacific Time Zone, and receives the same network feed as the West Coast. Weekday primetime runs from 7 to 10 pm. Effectively, programs are viewed at the same local hour as those in the Central Time Zone. The city's only cable television provider is General Communication, Inc. (GCI). However, Dish Network and DirecTV offer satellite television service in Anchorage and the surrounding area; and uses East Coast feeds.


title: Anchorage, Alaska

text: There are many radio stations in Anchorage; see List of radio stations in Alaska for more information.


title: Anchorage, Alaska

text: Providence Alaska Medical Center on Providence Drive in Anchorage is the largest hospital in Alaska and is part of Providence Health & Services in Alaska, Washington, Oregon, and California. It features the state's most comprehensive range of services. Providence Health System has a history of serving Alaska, beginning when the Sisters of Providence of Montreal first brought health care to Nome in 1902. As the territory grew during the following decades, so did efforts to provide care. Hospitals were opened in Fairbanks in 1910 and Anchorage in 1937.


title: Anchorage, Alaska

text: Alaska Regional Hospital on DeBarr Road opened in 1958 as Anchorage Presbyterian Hospital, downtown at 825 L Street. This predecessor to Alaska Regional was a joint venture between local physicians and the Presbyterian Church. In 1976 the hospital moved to its present location on DeBarr Road, and is now a 254-bed licensed and accredited facility. Alaska Regional has expanded services and in 1994, Alaska Regional joined with HCA, one of the nation's largest healthcare providers.


title: Anchorage, Alaska

text: Alaska Native Medical Center on Tudor Road provides medical care and therapeutic health care to Alaska natives—229 tribes—at the Anchorage site and at 15 satellite facilities throughout the state. ANMC specialists also travel to clinics in the bush to provide care. The 150-bed hospital is also a teaching center for the University of Washington's regional medical education program. ANMC houses an office of the Centers for Disease Control and Prevention. The Alaska Native Tribal Health Consortium and Southcentral Foundation jointly own and manage ANMC.


title: Anchorage, Alaska

text: Electric power in the Anchorage area is provided by Chugach Electric Association, a nonprofit, member-owned cooperative founded in 1948. From 1932 to 2020, the Municipality of Anchorage operated its own electric utility, Municipal Light & Power (ML&P). Historically, ML&P served the older, more urbanized regions of the city, while Chugach served newer areas of town, suburbs, and rural areas. Chugach acquired ML&P in 2020, with the sale finalized in October. Post-acquisition, the Chugach cooperative had over 92,000 members.


title: Anchorage, Alaska

text: Most homes have natural gas-fueled heat. ENSTAR Natural Gas Company is the sole provider for Anchorage, servicing some 90-percent of the city's population.


title: Anchorage, Alaska

text: The Municipality of Anchorage owns and operates the Anchorage Water and Wastewater Utility, serving some 55,000 customer accounts with water from Eklutna Lake, which is mainly meltwater from Eklutna Glacier. Anchorage Municipal Solid Waste Services and Anchorage Refuse conduct trash removal in the city depending on location.


title: Anchorage, Alaska

text: Alaskans do not use numerical route designations in everyday discourse, preferring the named designations—in this case the Seward Highway (for AK-1 south of the city), the Glenn Highway (for AK-1 northeast of the city), and the Parks Highway (for AK-3).


title: Anchorage, Alaska

text: On and off since the 1960s, the Alaska Department of Transportation & Public Facilities, in coordination with the Federal Highway Administration and the Municipality of Anchorage (or the lineal predecessors of those entities), have been exploring the concept of a roadway connecting the endpoints of the Seward and Glenn highways. The project is called "Highway to Highway", and the most recent concept for this project is that of a "trenched" freeway through the heart of Anchorage.


title: Anchorage, Alaska

text: Highway to Highway was included in the 2005 Long Range Transportation Plan, and would cost at least $575 million ($ million in dollars). – by far the largest urban infrastructure project in Alaska's history.


title: Anchorage, Alaska

text: Anchorage has a bus system called People Mover, with a hub downtown and satellite hubs at Dimond Center and Muldoon Mall. The People Mover provides carpool organization services. The public paratransit service known as AnchorRides provides point-to-point accessible transportation services to seniors and those who experience disabilities.


title: Anchorage, Alaska

text: The Alaska Railroad offers year-round freight service along the length of its rail system between Seward (the southern terminus of the system), Fairbanks (the northern terminus of the system), and Whittier (a deep water, ice-free port). Daily passenger service is available during summer (May 15 – September 15), but is reduced to one round-trip per week between Anchorage and Fairbanks during the winter. Passenger terminals exist at Talkeetna, Denali National Park, Fairbanks, and several other locations. These communities are also served by bus line from Anchorage. The Ship Creek Shuttle connects downtown with the Ship Creek area, including stops at the Alaska Railroad depot.


title: Anchorage, Alaska

text: Anchorage also is conducting a feasibility study on a commuter rail and light rail system. For the commuter rail system, Anchorage would use existing Alaska Railroad tracks to provide service to Whittier, Palmer, Seward, Wasilla, and Eagle River.


title: Anchorage, Alaska

text: The Ted Stevens Anchorage International Airport, south of downtown Anchorage, is the airline hub for the state, served by many national and international airlines, including Seattle-based Alaska Airlines as well as many intrastate airlines and charter air services. The airport is the primary international air freight gateway in the nation. By weight, five percent of the value of all United States international air cargo moved through Anchorage in 2008. During the COVID-19 pandemic, it was briefly the busiest airport in the United States due to sustained volume of cargo flights through Alaska while passenger travel sharply decreased in other American airports. Next to Ted Stevens Anchorage International Airport is Lake Hood Seaplane Base, the largest Seaplane Base in the world. Merrill Field, a general aviation airport on the edge of downtown, was the 87th-busiest airport in the nation in 2010. There are also ten smaller private (mostly Department of Transportation) general aviation airports within the city limits.


title: Rubik's Cube

text: The Rubik's Cube is a 3-D combination puzzle originally invented in 1974 by Hungarian sculptor and professor of architecture Ernő Rubik. Originally called the Magic Cube, the puzzle was licensed by Rubik to be sold by Pentangle Puzzles in the UK in 1978, and then by Ideal Toy Corp in 1980 via businessman Tibor Laczi and Seven Towns founder Tom Kremer. The cube was released internationally in 1980 and became one of the most recognized icons in popular culture. It won the 1980 German Game of the Year special award for Best Puzzle. , 350 million cubes had been sold worldwide, making it the world's bestselling puzzle game and bestselling toy. The Rubik's Cube was inducted into the US National Toy Hall of Fame in 2014.


title: Rubik's Cube

text: On the original classic Rubik's Cube, each of the six faces was covered by nine stickers, each of one of six solid colours: white, red, blue, orange, green, and yellow. Some later versions of the cube have been updated to use coloured plastic panels instead, which prevents peeling and fading. Since 1988, the arrangement of colours has been standardised with white opposite yellow, blue opposite green, and orange opposite red, and the red, white, and blue arranged clockwise in that order. On early cubes, the position of the colours varied from cube to cube. An internal pivot mechanism enables each face to turn independently, thus mixing up the colours. For the puzzle to be solved, each face must be returned to have only one colour. Similar puzzles have now been produced with various numbers of sides, dimensions, and stickers, not all of them by Rubik.


title: Rubik's Cube

text: Although the Rubik's Cube reached its height of mainstream popularity in the 1980s, it is still widely known and used. Many speedcubers continue to practise it and similar puzzles, and compete for the fastest times in various categories. Since 2003, the World Cube Association, the international governing body of the Rubik's Cube, has organised competitions worldwide and recognises world records.


title: Rubik's Cube

text: In March 1970, Larry D. Nichols invented a 2×2×2 "Puzzle with Pieces Rotatable in Groups" and filed a Canadian patent application for it. Nichols's cube was held together by magnets. Nichols was granted on 11 April 1972, two years before Rubik invented his Cube.


title: Rubik's Cube

text: On 9 April 1970, Frank Fox applied to patent an "amusement device", a type of sliding puzzle on a spherical surface with "at least two 3×3 arrays" intended to be used for the game of noughts and crosses. He received his UK patent (1344259) on 16 January 1974.


title: Rubik's Cube

text: In the mid-1970s, Ernő Rubik worked at the Department of Interior Design at the Academy of Applied Arts and Crafts in Budapest. Although it is widely reported that the Cube was built as a teaching tool to help his students understand 3D objects, his actual purpose was solving the structural problem of moving the parts independently without the entire mechanism falling apart. He did not realise that he had created a puzzle until the first time he scrambled his new Cube and then tried to restore it. Rubik applied for a patent in Hungary for his "Magic Cube" () on 30 January 1975, and HU170062 was granted later that year.


title: Rubik's Cube

text: The first test batches of the Magic Cube were produced in late 1977 and released in Budapest toy shops. Magic Cube was held together with interlocking plastic pieces that prevented the puzzle being easily pulled apart, unlike the magnets in Nichols's design. With Ernő Rubik's permission, businessman Tibor Laczi took a Cube to Germany's Nuremberg Toy Fair in February 1979 in an attempt to popularise it. It was noticed by Seven Towns founder Tom Kremer, and they signed a deal with Ideal Toys in September 1979 to release the Magic Cube worldwide. Ideal wanted at least a recognisable name to trademark; that arrangement put Rubik in the spotlight because the Magic Cube was renamed after its inventor in 1980. The puzzle made its international debut at the toy fairs of London, Paris, Nuremberg, and New York in January and February 1980.


title: Rubik's Cube

text: After its international debut, the progress of the Cube towards the toy shop shelves of the West was briefly halted so that it could be manufactured to Western safety and packaging specifications. A lighter Cube was produced, and Ideal decided to rename it. "The Gordian Knot" and "Inca Gold" were considered, but the company finally decided on "Rubik's Cube", and the first batch was exported from Hungary in May 1980.


title: Rubik's Cube

text: After the first batches of Rubik's Cubes were released in May 1980, initial sales were modest, but Ideal began a television advertising campaign in the middle of the year which it supplemented with newspaper advertisements. At the end of 1980, Rubik's Cube won a German Game of the Year special award and won similar awards for best toy in the UK, France, and the US. By 1981, Rubik's Cube had become a craze, and it is estimated that in the period from 1980 to 1983 around 200 million Rubik's Cubes were sold worldwide. In March 1981, a speedcubing championship organised by the Guinness Book of World Records was held in Munich, and a Rubik's Cube was depicted on the front cover of "Scientific American" that same month. In June 1981, "The Washington Post" reported that Rubik's Cube is "a puzzle that's moving like fast food right now ... this year's Hoola Hoop or Bongo Board", and by September 1981, "New Scientist" noted that the cube had "captivated the attention of children of ages from 7 to 70 all over the world this summer."


title: Rubik's Cube

text: As most people could solve only one or two sides, numerous books were published including David Singmaster's "Notes on Rubik's "Magic Cube"" (1980) and Patrick Bossert's "You Can Do the Cube" (1981). At one stage in 1981, three of the top ten best selling books in the US were books on solving Rubik's Cube, and the best-selling book of 1981 was James G. Nourse's "The Simple Solution to Rubik's Cube" which sold over 6 million copies. In 1981, the Museum of Modern Art in New York exhibited a Rubik's Cube, and at the 1982 World's Fair in Knoxville, Tennessee a six-foot Cube was put on display. ABC Television even developed a cartoon show called "Rubik, the Amazing Cube". In June 1982, the First Rubik's Cube World Championship took place in Budapest and would become the only competition recognized as official until the championship was revived in 2003.


title: Rubik's Cube

text: In October 1982, "The New York Times" reported that sales had fallen and that "the craze has died", and by 1983 it was clear that sales had plummeted. However, in some countries such as China and the USSR, the craze had started later and demand was still high because of a shortage of Cubes.


title: Rubik's Cube

text: Rubik's Cubes continued to be marketed and sold throughout the 1980s and 1990s, but it was not until the early 2000s that interest in the Cube began increasing again. In the US, sales doubled between 2001 and 2003, and "The Boston Globe" remarked that it was "becoming cool to own a Cube again". The 2003 World Rubik's Games Championship was the first speedcubing tournament since 1982. It was held in Toronto and was attended by 83 participants. The tournament led to the formation of the World Cube Association in 2004. Annual sales of Rubik branded cubes were said to have reached 15 million worldwide in 2008. Part of the new appeal was ascribed to the advent of Internet video sites, such as YouTube, which allowed fans to share their solving strategies. Following the expiration of Rubik's patent in 2000, other brands of cubes appeared, especially from Chinese companies. Many of these Chinese branded cubes have been engineered for speed and are favoured by speedcubers. On 27 October 2020, Spin Master said it will pay $50 million to buy the Rubik's Cube brand.


title: Rubik's Cube

text: Taking advantage of an initial shortage of cubes, many imitations and variations appeared, many of which may have violated one or more patents. In 2000 the patents expired, and since then, many Chinese companies have produced copies of, modifications and improvements upon the Rubik and V-Cube designs.


title: Rubik's Cube

text: Nichols assigned his patent to his employer Moleculon Research Corp., which sued Ideal in 1982. In 1984, Ideal lost the patent infringement suit and appealed. In 1986, the appeals court affirmed the judgment that Rubik's 2×2×2 Pocket Cube infringed Nichols's patent, but overturned the judgment on Rubik's 3×3×3 Cube.


title: Rubik's Cube

text: Even while Rubik's patent application was being processed, Terutoshi Ishigi, a self-taught engineer and ironworks owner near Tokyo, filed for a Japanese patent for a nearly identical mechanism, which was granted in 1976 (Japanese patent publication JP55-008192). Until 1999, when an amended Japanese patent law was enforced, Japan's patent office granted Japanese patents for non-disclosed technology within Japan without requiring worldwide novelty. Hence, Ishigi's patent is generally accepted as an independent reinvention at that time. Rubik applied for more patents in 1980, including another Hungarian patent on 28 October. In the United States, Rubik was granted on 29 March 1983, for the Cube. This patent expired in 2000.


title: Rubik's Cube

text: Rubik's Brand Ltd. also holds the registered trademarks for the word "Rubik" and "Rubik's" and for the 2D and 3D visualisations of the puzzle. The trademarks have been upheld by a ruling of the General Court of the European Union on 25 November 2014 in a successful defence against a German toy manufacturer seeking to invalidate them. However, European toy manufacturers are allowed to create differently shaped puzzles that have a similar rotating or twisting functionality of component parts such as for example Skewb, Pyraminx or Impossiball.


title: Rubik's Cube

text: On 10 November 2016, Rubik's Cube lost a ten-year battle over a key trademark issue. The European Union's highest court, the Court of Justice, ruled that the puzzle's shape was not sufficient to grant it trademark protection.


title: Rubik's Cube

text: A standard Rubik's Cube measures on each side. The puzzle consists of 26 unique miniature cubes, also known as "cubies" or "cubelets". Each of these includes a concealed inward extension that interlocks with the other cubes while permitting them to move to different locations. However, the centre cube of each of the six faces is merely a single square façade; all six are affixed to the core mechanism. These provide structure for the other pieces to fit into and rotate around. Hence, there are 21 pieces: a single core piece consisting of three intersecting axes holding the six centre squares in place but letting them rotate, and 20 smaller plastic pieces that fit into it to form the assembled puzzle.


title: Rubik's Cube

text: Each of the six centre pieces pivots on a screw (fastener) held by the centre piece, a "3D cross". A spring between each screw head and its corresponding piece tensions the piece inward, so that collectively, the whole assembly remains compact but can still be easily manipulated. The screw can be tightened or loosened to change the "feel" of the Cube. Newer official Rubik's brand cubes have rivets instead of screws and cannot be adjusted. However, Old Cubes made by the Rubik's Brand Ltd. and from dollar stores do not have screws or springs, all they have is a plastic clip to keep the centre piece in place and freely rotate.


title: Rubik's Cube

text: The Cube can be taken apart without much difficulty, typically by rotating the top layer by 45° and then prying one of its edge cubes away from the other two layers. Consequently, it is a simple process to "solve" a Cube by taking it apart and reassembling it in a solved state.


title: Rubik's Cube

text: There are six central pieces that show one coloured face, twelve edge pieces that show two coloured faces, and eight corner pieces that show three coloured faces. Each piece shows a unique colour combination, but not all combinations are present (for example, if red and orange are on opposite sides of the solved Cube, there is no edge piece with both red and orange sides). The location of these cubes relative to one another can be altered by twisting an outer third of the Cube by increments of 90 degrees, but the location of the coloured sides relative to one another in the completed state of the puzzle cannot be altered; it is fixed by the relative positions of the centre squares. However, Cubes with alternative colour arrangements also exist; for example, with the yellow face opposite the green, the blue face opposite the white, and red and orange remaining opposite each other.


title: Rubik's Cube

text: Douglas Hofstadter, in the July 1982 issue of "Scientific American", pointed out that Cubes could be coloured in such a way as to emphasise the corners or edges, rather than the faces as the standard colouring does; but neither of these alternative colourings has ever become popular.


title: Rubik's Cube

text: The puzzle was originally advertised as having "over 3,000,000,000 (three billion) combinations but only one solution". Depending on how combinations are counted, the actual number is significantly higher.


title: Rubik's Cube

text: The original (3×3×3) Rubik's Cube has eight corners and twelve edges. There are 8! (40,320) ways to arrange the corner cubes. Each corner has three possible orientations, although only seven (of eight) can be oriented independently; the orientation of the eighth (final) corner depends on the preceding seven, giving 3 (2,187) possibilities. There are 12!/2 (239,500,800) ways to arrange the edges, restricted from 12! because edges must be in an even permutation exactly when the corners are. (When arrangements of centres are also permitted, as described below, the rule is that the combined arrangement of corners, edges, and centres must be an even permutation.) Eleven edges can be flipped independently, with the flip of the twelfth depending on the preceding ones, giving 2 (2,048) possibilities.


title: Rubik's Cube

text: which is approximately 43 quintillion. To put this into perspective, if one had one standard-sized Rubik's Cube for each permutation, one could cover the Earth's surface 275 times, or stack them in a tower 261 light-years high.


title: Rubik's Cube

text: The preceding figure is limited to permutations that can be reached solely by turning the sides of the cube. If one considers permutations reached through disassembly of the cube, the number becomes twelve times larger:


title: Rubik's Cube

text: which is approximately 519 quintillion possible arrangements of the pieces that make up the cube, but only one in twelve of these are actually solvable. This is because there is no sequence of moves that will swap a single pair of pieces or rotate a single corner or edge cube. Thus, there are 12 possible sets of reachable configurations, sometimes called "universes" or "orbits", into which the cube can be placed by dismantling and reassembling it.


title: Rubik's Cube

text: The preceding numbers assume the centre faces are in a fixed position. If one considers turning the whole cube to be a different permutation, then each of the preceding numbers should be multiplied by 24. A chosen colour can be on one of six sides, and then one of the adjacent colours can be in one of four positions; this determines the positions of all remaining colours.


title: Rubik's Cube

text: The original Rubik's Cube had no orientation markings on the centre faces (although some carried the words "Rubik's Cube" on the centre square of the white face), and therefore solving it does not require any attention to orienting those faces correctly. However, with marker pens, one could, for example, mark the central squares of an unscrambled Cube with four coloured marks on each edge, each corresponding to the colour of the adjacent face; a cube marked in this way is referred to as a "supercube". Some Cubes have also been produced commercially with markings on all of the squares, such as the Lo Shu magic square or playing card suits. Cubes have also been produced where the nine stickers on a face are used to make a single larger picture, and centre orientation matters on these as well. Thus one can nominally solve a Cube yet have the markings on the centres rotated; it then becomes an additional test to solve the centres as well.


title: Rubik's Cube

text: Marking Rubik's Cube's centres increases its difficulty, because this expands the set of distinguishable possible configurations. There are 4/2 (2,048) ways to orient the centres since an even permutation of the corners implies an even number of quarter turns of centres as well. In particular, when the Cube is unscrambled apart from the orientations of the central squares, there will always be an even number of centre squares requiring a quarter turn. Thus orientations of centres increases the total number of possible Cube permutations from 43,252,003,274,489,856,000 (4.3×10) to 88,580,102,706,155,225,088,000 (8.9×10).


title: Rubik's Cube

text: When turning a cube over is considered to be a change in permutation then we must also count arrangements of the centre faces. Nominally there are 6! ways to arrange the six centre faces of the cube, but only 24 of these are achievable without disassembly of the cube. When the orientations of centres are also counted, as above, this increases the total number of possible Cube permutations from 88,580,102,706,155,225,088,000 (8.9×10) to 2,125,922,464,947,725,402,112,000 (2.1×10).


title: Rubik's Cube

text: In Rubik's cubers' parlance, a memorised sequence of moves that has a desired effect on the cube is called an "algorithm". This terminology is derived from the mathematical use of "algorithm", meaning a list of well-defined instructions for performing a task from a given initial state, through well-defined successive states, to a desired end-state. Each method of solving the Cube employs its own set of algorithms, together with descriptions of what effect the algorithm has, and when it can be used to bring the cube closer to being solved.


title: Rubik's Cube

text: Many algorithms are designed to transform only a small part of the cube without interfering with other parts that have already been solved so that they can be applied repeatedly to different parts of the cube until the whole is solved. For example, there are well-known algorithms for cycling three corners without changing the rest of the puzzle or flipping the orientation of a pair of edges while leaving the others intact.


title: Rubik's Cube

text: Some algorithms do have a certain desired effect on the cube (for example, swapping two corners) but may also have the side-effect of changing other parts of the cube (such as permuting some edges). Such algorithms are often simpler than the ones without side effects and are employed early on in the solution when most of the puzzle has not yet been solved and the side effects are not important. Towards the end of the solution, the more specific (and usually more complicated) algorithms are used instead.


title: Rubik's Cube

text: Rubik's Cube lends itself to the application of mathematical group theory, which has been helpful for deducing certain algorithms – in particular, those which have a "commutator" structure, namely "XYX""Y" (where "X" and "Y" are specific moves or move-sequences and "X" and "Y" are their respective inverses), or a "conjugate" structure, namely "XYX", often referred to by speedcubers colloquially as a "setup move". In addition, the fact that there are well-defined subgroups within the Rubik's Cube group enables the puzzle to be learned and mastered by moving up through various self-contained "levels of difficulty". For example, one such "level" could involve solving cubes that have been scrambled using only 180-degree turns. These subgroups are the principle underlying the computer cubing methods by Thistlethwaite and Kociemba, which solve the cube by further reducing it to another subgroup.


title: Rubik's Cube

text: Many 3×3×3 Rubik's Cube enthusiasts use a notation developed by David Singmaster to denote a sequence of moves, referred to as "Singmaster notation". Its relative nature allows algorithms to be written in such a way that they can be applied regardless of which side is designated the top or how the colours are organised on a particular cube.


title: Rubik's Cube

text: When a prime symbol ( ′ ) follows a letter, it denotes an anticlockwise face turn; while a letter without a prime symbol denotes a clockwise turn. These directions are as one is looking at the specified face. A letter followed by a 2 (occasionally a superscript ) denotes two turns, or a 180-degree turn. "R" is right side clockwise, but "R′" is right side anticlockwise. The letters "x", "y", and "z" are used to indicate that the entire Cube should be turned about one of its axes, corresponding to R, U, and F turns respectively. When "x", "y", or "z" is primed, it is an indication that the cube must be rotated in the opposite direction. When "x", "y", or "z" is squared, the cube must be rotated 180 degrees.


title: Rubik's Cube

text: The most common deviation from Singmaster notation, and in fact the current official standard, is to use "w", for "wide", instead of lowercase letters to represent moves of two layers; thus, a move of "Rw" is equivalent to one of "r".


title: Rubik's Cube

text: For methods using middle-layer turns (particularly corners-first methods), there is a generally accepted "MES" extension to the notation where letters "M", "E", and "S" denote middle layer turns. It was used e.g. in Marc Waterman's Algorithm.


title: Rubik's Cube

text: The 4×4×4 and larger cubes use an extended notation to refer to the additional middle layers. Generally speaking, uppercase letters ("F B U D L R") refer to the outermost portions of the cube (called faces). Lowercase letters ("f b u d l r") refer to the inner portions of the cube (called slices). An asterisk (L*), a number in front of it (2L), or two layers in parentheses (Ll), means to turn the two layers at the same time (both the inner and the outer left faces) For example: ("Rr")<nowiki>'</nowiki> "l"2 "f"<nowiki>'</nowiki> means to turn the two rightmost layers anticlockwise, then the left inner layer twice, and then the inner front layer anticlockwise. By extension, for cubes of 6×6×6 and larger, moves of three layers are notated by the number 3, for example, 3L.


title: Rubik's Cube

text: An alternative notation, Wolstenholme notation, is designed to make memorising sequences of moves easier for novices. This notation uses the same letters for faces except it replaces U with T (top), so that all are consonants. The key difference is the use of the vowels O, A, and I for clockwise, anticlockwise, and twice (180-degree) turns, which results in word-like sequences such as LOTA RATO LATA ROTI (equivalent to LU′ R′ U L′ U′ R U2 in Singmaster notation). The addition of a C implies rotation of the entire cube, so ROC is the clockwise rotation of the cube around its right face. Middle layer moves are denoted by adding an M to the corresponding face move, so RIM means a 180-degree turn of the middle layer adjacent to the R face.


title: Rubik's Cube

text: Another notation appeared in the 1981 book "The Simple Solution to Rubik's Cube". Singmaster notation was not widely known at the time of publication. The faces were named Top (T), Bottom (B), Left (L), Right (R), Front (F), and Posterior (P), with + for clockwise, – for anticlockwise, and 2 for 180-degree turns.


title: Rubik's Cube

text: Another notation appeared in the 1982 "The Ideal Solution" book for Rubik's Revenge. Horizontal planes were noted as tables, with table 1 or T1 starting at the top. Vertical front to back planes were noted as books, with book 1 or B1 starting from the left. Vertical left to right planes were noted as windows, with window 1 or W1 starting at the front. Using the front face as a reference view, table moves were left or right, book moves were up or down, and window moves were clockwise or anticlockwise.


title: Rubik's Cube

text: The repetition of any given move sequence on a cube which is initially in solved state will eventually return the cube back to its solved state: the smallest number of iterations required is the period of the sequence. For example, the 180-degree turn of any side has period 2 (e.g. "{U}"); the 90-degree turn of any side has period 4 (e.g. "{R}"). The maximum period for a move sequence is 1260: for example, allowing for full rotations, "{F x}" or "{R y}" or "{U z}"; not allowing for rotations, "{D R' U M}", or "{B E L' F}", or "{S' U' B D}"; only allowing for clockwise quarter turns, "{U R S U L}", or "{F L E B L}", or "{R U R D S}"; only allowing for lateral clockwise quarter turns, "{F B L F B R F U}", or "{U D R U D L U F}", or "{R L D R L U R F}".


title: Rubik's Cube

text: Although there are a significant number of possible permutations for Rubik's Cube, a number of solutions have been developed which allow solving the cube in well under 100 moves.


title: Rubik's Cube

text: Many general solutions for the Cube have been discovered independently. David Singmaster first published his solution in the book "Notes on Rubik's "Magic Cube"" in 1981. This solution involves solving the Cube layer by layer, in which one layer (designated the top) is solved first, followed by the middle layer, and then the final and bottom layer. After sufficient practice, solving the Cube layer by layer can be done in under one minute. Other general solutions include "corners first" methods or combinations of several other methods. In 1982, David Singmaster and Alexander Frey hypothesised that the number of moves needed to solve the Cube, given an ideal algorithm, might be in "the low twenties". In 2007, Daniel Kunkle and Gene Cooperman used computer search methods to demonstrate that any 3×3×3 Rubik's Cube configuration can be solved in 26 moves or fewer.


title: Rubik's Cube

text: In 2008, Tomas Rokicki lowered that number to 22 moves, and in July 2010, a team of researchers including Rokicki, working with Google, proved that the so-called "God's number" for Rubik's Cube is 20. This means that all initial configurations can be solved in 20 moves or less, and some (in fact millions) require 20. More generally, it has been shown that an "n"×"n"×"n" Rubik's Cube can be solved optimally in Θ("n" / log("n")) moves.


title: Rubik's Cube

text: A solution commonly used by speedcubers was developed by Jessica Fridrich. This method is called CFOP standing for "cross, F2L, OLL, PLL". It is similar to the layer-by-layer method but employs the use of a large number of algorithms, especially for orienting and permuting the last layer. The cross is done first, followed by first layer corners and second layer edges simultaneously, with each corner paired up with a second-layer edge piece, thus completing the first two layers (F2L). This is then followed by orienting the last layer, then permuting the last layer (OLL and PLL respectively). Fridrich's solution requires learning roughly 120 algorithms but allows the Cube to be solved in only 55 moves on average.


title: Rubik's Cube

text: A now well-known method was developed by Lars Petrus. In this method, a 2×2×2 section is solved first, followed by a 2×2×3, and then the incorrect edges are solved using a three-move algorithm, which eliminates the need for a possible 32-move algorithm later. The principle behind this is that in layer-by-layer, one must constantly break and fix the completed layer(s); the 2×2×2 and 2×2×3 sections allow three or two layers (respectively) to be turned without ruining progress. One of the advantages of this method is that it tends to give solutions in fewer moves. For this reason, the method is also popular for fewest move competitions.


title: Rubik's Cube

text: The Roux Method, developed by Gilles Roux, is similar to the Petrus method in that it relies on block building rather than layers, but derives from corners-first methods. In Roux, a 3×2×1 block is solved, followed by another 3×2×1 on the opposite side. Next, the corners of the top layer are solved. The cube can then be solved using only moves of the U layer and M slice.


title: Rubik's Cube

text: Most beginner solution methods involve solving the cube one layer at a time, using algorithms that preserve what has already been solved. The easiest layer by layer methods require only 3–8 algorithms.


title: Rubik's Cube

text: In 1981, thirteen-year-old Patrick Bossert developed a solution for solving the cube, along with a graphical notation, designed to be easily understood by novices. It was subsequently published as "You Can Do The Cube" and became a best-seller.


title: Rubik's Cube

text: In 1997, Denny Dedmore published a solution described using diagrammatic icons representing the moves to be made, instead of the usual notation.


title: Rubik's Cube

text: Philip Marshall's "The Ultimate Solution to Rubik's Cube" takes a different approach, averaging only 65 twists yet requiring the memorisation of only "two" algorithms. The cross is solved first, followed by the remaining edges, then five corners, and finally the last three corners.


title: Rubik's Cube

text: The most move optimal online Rubik's Cube solver programs use Herbert Kociemba's Two-Phase Algorithm which can typically determine a solution of 20 moves or fewer. The user has to set the colour configuration of the scrambled cube, and the program returns the steps required to solve it.


title: Rubik's Cube

text: Speedcubing (or speedsolving) is the practice of trying to solve a Rubik's Cube in the shortest time possible. There are a number of speedcubing competitions that take place around the world.


title: Rubik's Cube

text: A speedcubing championship organised by the Guinness Book of World Records was held in Munich on 13 March 1981. The contest used standardised scrambling and fixed inspection times, and the winners were Ronald Brinkmann and Jury Fröschl with times of 38.0 seconds. The first world championship was the 1982 World Rubik's Cube Championship held in Budapest on 5 June 1982, which was won by Minh Thai, a Vietnamese student from Los Angeles, with a time of 22.95 seconds.


title: Rubik's Cube

text: Since 2003, the winner of a competition is determined by taking the average time of the middle three of five attempts. However, the single best time of all tries is also recorded.


title: Rubik's Cube

text: In addition to the main 3x3x3 event, the WCA also holds events where the cube is solved in different ways:


title: Rubik's Cube

text: In Blindfolded Solving, the contestant first studies the scrambled cube (i.e., looking at it normally with no blindfold), and is then blindfolded before beginning to turn the cube's faces. Their recorded time for this event includes both the time spent memorizing the cube and the time spent manipulating it.


title: Rubik's Cube

text: In Multiple Blindfolded, all of the cubes are memorised, and then all of the cubes are solved once blindfolded; thus, the main challenge is memorising many – often ten or more – separate cubes. The event is scored not by time but by the number of points achieved after the one-hour time limit has elapsed. The number of points achieved is equal to the number of cubes solved correctly, minus the number of cubes unsolved after the end of the attempt, where a greater number of points is better. If multiple competitors achieve the same number of points, rankings are assessed based on the total time of the attempt, with a shorter time being better.


title: Rubik's Cube

text: There are many different variations of Rubik's Cubes. The most common class of variants changes the "order" of the cube, defined by the number of layers in each dimension or equivalently by the number of pieces along each edge (including corners). The 2×2×2 (Pocket/Mini Cube), the standard 3×3×3 cube, the 4×4×4 (Rubik's Revenge/Master Cube), and the 5×5×5 (Professor's Cube) are the most well known, as they are all available under the official Rubik's brand. The WCA sanctions speedsolving competitions for cube orders up to 7x7x7. These "big cubes" represent about the limit of practicality for the purpose of competitive speedsolving, as the cubes become increasingly ungainly and prone to mechanical failure (such as "popping", where one or more pieces become dislodged from the puzzle), and average solve times increase quadratically with each larger order, in proportion to the number of total "facelets" of the cube.


title: Rubik's Cube

text: Even larger cubes based on the V-Cube patents are commercially available to the mass-market from non-licensed manufacturers, most of them Chinese firms who also produce popular cubes designed for speed-solving. The 17×17×17 "Over The Top" cube (available late 2011) was until December 2017 the largest commercially sold cube, and the most expensive, costing over US$2000. A mass-produced 17×17×17 was later introduced by the Chinese manufacturer YuXin. A working design for a 22×22×22 cube exists and was demonstrated in January 2016, and a 33×33×33 in December 2017, though designs this large are not currently mass-produced. Chinese manufacturer ShengShou has been producing cubes in all sizes from 2×2×2 to 15×15×15 (as of May 2020), and have also come out with a 17×17×17. The largest currently mass-produced cube is 21x21x21, made by MoYu beginning in 2021, and costing between $1100 and $1600.


title: Rubik's Cube

text: There are many variations of the original cube, some of which are made by Rubik. The mechanical products include Rubik's Magic, 360, and Twist. Also, electronics like Rubik's Revolution and Slide, were also inspired by the original. One of the 3×3×3 Cube variants is Rubik's TouchCube. Sliding a finger across its faces causes its patterns of coloured lights to rotate the same way they would on a mechanical cube. The TouchCube also has buttons for hints and self-solving, and it includes a charging stand. The TouchCube was introduced at the American International Toy Fair in New York on 15 February 2009.


title: Rubik's Cube

text: The Cube has inspired an entire category of similar puzzles, commonly referred to as "twisty puzzles", which includes the cubes of different sizes mentioned above, as well as various other geometric shapes. Some such shapes include the tetrahedron (Pyraminx), the octahedron (Skewb Diamond), the dodecahedron (Megaminx), and the icosahedron (Dogic). There are also puzzles that change shape such as Rubik's Snake and the Square One.


title: Rubik's Cube

text: In 2011, Guinness World Records awarded the "largest order Rubiks magic cube" to a 17×17×17 cube, made by Oskar van Deventer. On 2 December 2017, Grégoire Pfennig announced that he had broken this record, with a 33×33×33 cube, and that his claim had been submitted to Guinness for verification. On 8 April 2018, Grégoire Pfennig announced another world record, the 2x2x50 cube. Whether this is a replacement for the 33x33x33 record, or an additional record, remains to be seen.


title: Rubik's Cube

text: Some puzzles have also been created in the shape of Kepler–Poinsot polyhedra, such as Alexander's Star (a great dodecahedron). Grégoire Pfennig has also created at least one puzzle in the shape of a small stellated dodecahedron.


title: Rubik's Cube

text: Puzzles have been built resembling Rubik's Cube, or based on its inner workings. For example, a cuboid is a puzzle based on Rubik's Cube, but with different functional dimensions, such as 2×2×4, 2×3×4, and 3×3×5. Many cuboids are based on 4×4×4 or 5×5×5 mechanisms, via building plastic extensions or by directly modifying the mechanism.


title: Rubik's Cube

text: Some custom puzzles are not derived from any existing mechanism, such as the Gigaminx v1.5-v2, Bevel Cube, SuperX, Toru, Rua, and 1×2×3. These puzzles usually have a set of masters 3D printed, which then are copied using moulding and casting techniques to create the final puzzle.


title: Rubik's Cube

text: Other Rubik's Cube modifications include "shape mods", cubes that have been extended or truncated to form a new shape. An example of this is the Trabjer's Octahedron, which can be built by truncating and extending portions of a regular 3×3×3. Most shape modifications can be adapted to higher-order cubes. In the case of Tony Fisher's Rhombic Dodecahedron, there are 3×3×3, 4×4×4, 5×5×5, and 6×6×6 versions of the puzzle.


title: Rubik's Cube

text: Puzzles, like Rubik's Cube, can be simulated by computer software to provide very large puzzles that are impractical to build, as well as virtual puzzles that cannot be physically built, such as many higher dimensional analogues of the Rubik's Cube.


title: Rubik's Cube

text: Google has released the Chrome Cube Lab in association with Ernő Rubik. The site has various interactive objects based on Rubik's Cube. Customised versions of Rubik's Cube can be created and uploaded.


title: Dolphin

text: A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the brackish dolphins), and the extinct Lipotidae (baiji or Chinese river dolphin). There are 40 extant species named as dolphins.


title: Dolphin

text: Dolphins range in size from the and Maui's dolphin to the and orca. Various species of dolphins exhibit sexual dimorphism where the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers. Though not quite as flexible as seals, some dolphins can briefly travel at speeds of per hour or leap about . Dolphins use their conical teeth to capture fast-moving prey. They have well-developed hearing which is adapted for both air and water. It is so well developed that some can survive even if they are blind. Some species are well adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water.


title: Dolphin

text: Dolphins are widespread. Most species prefer the warm waters of the tropic zones, but some, such as the right whale dolphin, prefer colder climates. Dolphins feed largely on fish and squid, but a few, such as the orca, feed on large mammals such as seals. Male dolphins typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them. Mothers of some species fast and nurse their young for a relatively long period of time. Dolphins produce a variety of vocalizations, usually in the form of clicks and whistles.


title: Dolphin

text: Dolphins are sometimes hunted in places such as Japan, in an activity known as dolphin drive hunting. Besides drive hunting, they also face threats from bycatch, habitat loss, and marine pollution. Dolphins have been depicted in various cultures worldwide. Dolphins are sometimes kept in captivity and trained to perform tricks. The most common dolphin species in captivity is the bottlenose dolphin, while there are around 60 orcas in captivity.


title: Dolphin

text: The name is originally from Greek ("delphís"), "dolphin", which was related to the Greek ("delphus"), "womb". The animal's name can therefore be interpreted as meaning "a 'fish' with a womb". The name was transmitted via the Latin "delphinus" (the romanization of the later Greek δελφῖνος – "delphinos"), which in Medieval Latin became and in Old French "daulphin", which reintroduced the "ph" into the word "Dolphin". The term mereswine (that is, "sea pig") has also historically been used.


title: Dolphin

text: The term 'dolphin' can be used to refer to most species in the family Delphinidae (oceanic dolphins) and the river dolphin families Iniidae (South American river dolphins), Pontoporiidae (La Plata dolphin), Lipotidae (Yangtze river dolphin) and Platanistidae (Ganges river dolphin and Indus river dolphin).


title: Dolphin

text: This term has often been applied in the US, mainly in the fishing industry, to all small cetaceans (dolphins and porpoises) are considered to be porpoises, while the fish "dorado" is called dolphin fish. In common usage the term 'whale' is used only for the larger cetacean species, while the smaller ones with a beaked or longer nose are considered 'dolphins'. The name 'dolphin' is used casually as a synonym for bottlenose dolphin, the most common and familiar species of dolphin. There are six species of dolphins commonly thought of as whales, collectively known as blackfish: the orca, the melon-headed whale, the pygmy killer whale, the false killer whale, and the two species of pilot whales, all of which are classified under the family Delphinidae and qualify as dolphins. Although the terms 'dolphin' and 'porpoise' are sometimes used interchangeably, 'porpoise' usually refers to the Phocoenidae family, which have a shorter beak and spade-shaped teeth and differ in their behavior.


title: Dolphin

text: A group of dolphins is called a "school" or a "pod". Male dolphins are called "bulls", females called "cows" and young dolphins are called "calves".


title: Dolphin

text: In 1933, three hybrid dolphins beached off the Irish coast; they were hybrids between Risso's and bottlenose dolphins. This mating was later repeated in captivity, producing a hybrid calf. In captivity, a bottlenose and a rough-toothed dolphin produced hybrid offspring. A common-bottlenose hybrid lives at SeaWorld California. Other dolphin hybrids live in captivity around the world or have been reported in the wild, such as a bottlenose-Atlantic spotted hybrid. The best known hybrid is the wholphin, a false killer whale-bottlenose dolphin hybrid. The wolphin is a fertile hybrid. Two wolphins currently live at the Sea Life Park in Hawaii; the first was born in 1985 from a male false killer whale and a female bottlenose. Wolphins have also been observed in the wild.


title: Dolphin

text: Dolphins are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). They are related to the "Indohyus", an extinct chevrotain-like ungulate, from which they split approximately 48 million years ago.


title: Dolphin

text: The primitive cetaceans, or archaeocetes, first took to the sea approximately 49 million years ago and became fully aquatic by 5–10 million years later.


title: Dolphin

text: Archaeoceti is a parvorder comprising ancient whales. These ancient whales are the predecessors of modern whales, stretching back to their first ancestor that spent their lives near (rarely in) the water. Likewise, the archaeocetes can be anywhere from near fully terrestrial, to semi-aquatic to fully aquatic, but what defines an archaeocete is the presence of visible legs or asymmetrical teeth. Their features became adapted for living in the marine environment. Major anatomical changes include the hearing set-up that channeled vibrations from the jaw to the earbone which occurred with "Ambulocetus" 49 million years ago, a streamlining of the body and the growth of flukes on the tail which occurred around 43 million years ago with "Protocetus", the migration of the nasal openings toward the top of the cranium and the modification of the forelimbs into flippers which occurred with "Basilosaurus" 35 million years ago, and the shrinking and eventual disappearance of the hind limbs which took place with the first odontocetes and mysticetes 34 million years ago. The modern dolphin skeleton has two small, rod-shaped pelvic bones thought to be vestigial hind limbs. In October 2006, an unusual bottlenose dolphin was captured in Japan; it had small fins on each side of its genital slit, which scientists believe to be an unusually pronounced development of these vestigial hind limbs.


title: Dolphin

text: Today, the closest living relatives of cetaceans are the hippopotamuses; these share a semi-aquatic ancestor that branched off from other artiodactyls some 60 million years ago. Around 40 million years ago, a common ancestor between the two branched off into cetacea and anthracotheres; anthracotheres became extinct at the end of the Pleistocene two-and-a-half million years ago, eventually leaving only one surviving lineage: the two species of hippo.


title: Dolphin

text: Dolphins have torpedo-shaped bodies with generally non-flexible necks, limbs modified into flippers, a tail fin, and bulbous heads. Dolphin skulls have small eye orbits, long snouts, and eyes placed on the sides of its head; they lack external ear flaps. Dolphins range in size from the long and Maui's dolphin to the and orca. Overall, they tend to be dwarfed by other Cetartiodactyls. Several species have female-biased sexual dimorphism, with the females being larger than the males.


title: Dolphin

text: Dolphins have conical teeth, as opposed to porpoises' spade-shaped teeth. These conical teeth are used to catch swift prey such as fish, squid or large mammals, such as seal.


title: Dolphin

text: Breathing involves expelling stale air from their blowhole, in an upward blast, which may be visible in cold air, followed by inhaling fresh air into the lungs. Dolphins have rather small, unidentifiable spouts.


title: Dolphin

text: All dolphins have a thick layer of blubber, thickness varying on climate. This blubber can help with buoyancy, protection to some extent as predators would have a hard time getting through a thick layer of fat, and energy for leaner times; the primary usage for blubber is insulation from the harsh climate. Calves, generally, are born with a thin layer of blubber, which develops at different paces depending on the habitat.


title: Dolphin

text: Dolphins have a two-chambered stomach that is similar in structure to terrestrial carnivores. They have fundic and pyloric chambers.


title: Dolphin

text: Dolphins' reproductive organs are located inside the body, with genital slits on the ventral (belly) side. Males have two slits, one concealing the penis and one further behind for the anus. Females have one genital slit, housing the vagina and the anus, with a mammary slit on either side.


title: Dolphin

text: The integumentary system is an organ system mostly consisted of skin, hair, nails and endocrine glands. The skin of dolphins is very important as it is specialized to satisfy specific requirements. Some of these requirements include protection, fat storage, heat regulation, and sensory perception. The skin of a dolphin is made up of two parts: the epidermis and the blubber, which consists of two layers including the dermis and subcutis.


title: Dolphin

text: The dolphin's skin is known to have a smooth rubber texture and is without hair and glands, except mammary glands. At birth, a newborn dolphin has hairs lined up in a single band on both sides of the rostrum, which is their jaw, and usually has a total length of 16–17 cm .


title: Dolphin

text: Dolphins are a part of the species Cetacea. The epidermis of this species is characterized by the lack of keratin and by a prominent intertwine of epidermal rete pegs and long dermal papillae. The epidermal rete pegs are the epithelial extensions that project into the underlying connective tissue in both skin and mucous membranes. The dermal papillae are finger-like projections that help adhesion between the epidermal and dermal layers, as well as providing a larger surface area to nourish the epidermal layer. The thickness of a dolphin's epidermis varies, depending on species and age.


title: Dolphin

text: Blubber is found within the dermis and subcutis layer. The dermis blends gradually with the adipose layer, which is known as fat, because the fat may extend up to the epidermis border and collagen fiber bundles extend throughout the whole subcutaneous blubber which is fat found under the skin. The thickness of the subcutaneous blubber or fat depends on the dolphin's health, development, location, reproductive state, and how well it feeds. This fat is thickest on the dolphin's back and belly. Most of the dolphin's body fat is accumulated in a thick layer of blubber. Blubber differs from fat in that, in addition to fat cells, it contains a fibrous network of connective tissue.


title: Dolphin

text: The blubber functions to streamline the body and to form specialized locomotor structures such as the dorsal fin, propulsive fluke blades and caudal keels. There are many nerve endings that resemble small, onion-like configurations that are present in the superficial portion of the dermis. Mechanoreceptors are found within the interlocks of the epidermis with dermal ridges. There are nerve fibers in the dermis that extend to the epidermis. These nerve endings are known to be highly proprioceptive, which explains sensory perception. Proprioception, which is also known as kinesthesia, is the body's ability to sense its location, movements and actions. Dolphins are sensitive to vibrations and small pressure changes.


title: Dolphin

text: Blood vessels and nerve endings can be found within the dermis. There is a plexus of parallel running arteries and veins in the dorsal fin, fluke, and flippers. The blubber manipulates the blood vessels to help the dolphin stay warm. When the temperature drops, the blubber constricts the blood vessels to reduce blood flow in the dolphin. This allows the dolphin to spend less energy heating its own body, ultimately keeping the animal warmer without burning energy as quick. In order to release heat, the heat must pass the blubber layer. There are thermal windows that lack blubber, are not fully insulated and are somewhat thin and highly vascularized, including the dorsal fin, flukes, and flippers. These thermal windows are a good way for dolphins to get rid of excess heat if overheating. Additionally in order to conserve heat, dolphins use countercurrent heat exchange. Blood flows in different directions in order for heat to transfer across membranes. Heat from warm blood leaving the heart will heat up the cold blood that is headed back to the heart from the extremities, meaning that the heart always has warm blood and it decreases the heat lost to the water in those thermal windows.


title: Dolphin

text: Dolphins have two pectoral flippers, containing four digits, a boneless dorsal fin for stability, and a tail fin for propulsion. Although dolphins do not possess external hind limbs, some possess discrete rudimentary appendages, which may contain feet and digits. Dolphins are fast swimmers in comparison to seals which typically cruise at ; the orca, in comparison, can travel at speeds up to . The fusing of the neck vertebrae, while increasing stability when swimming at high speeds, decreases flexibility, which means they are unable to turn their heads. River dolphins have non-fused neck vertebrae and can turn their heads up to 90°. Dolphins swim by moving their tail fin and rear body vertically, while their flippers are mainly used for steering. Some species log out of the water, which may allow them to travel faster. Their skeletal anatomy allows them to be fast swimmers. All species have a dorsal fin to prevent themselves from involuntarily spinning in the water.


title: Dolphin

text: Some dolphins are adapted for diving to great depths. In addition to their streamlined bodies, some can selectively slow their heart rate to conserve oxygen. Some can also re-route blood from tissue tolerant of water pressure to the heart, brain and other organs. Their hemoglobin and myoglobin store oxygen in body tissues, and they have twice as much myoglobin as hemoglobin.


title: Dolphin

text: The dolphin ear has specific adaptations to the marine environment. In humans, the middle ear works as an impedance equalizer between the outside air's low impedance and the cochlear fluid's high impedance. In dolphins, and other marine mammals, there is no great difference between the outer and inner environments. Instead of sound passing through the outer ear to the middle ear, dolphins receive sound through the throat, from which it passes through a low-impedance fat-filled cavity to the inner ear. The dolphin ear is acoustically isolated from the skull by air-filled sinus pockets, which allow for greater directional hearing underwater. Dolphins send out high frequency clicks from an organ known as a melon. This melon consists of fat, and the skull of any such creature containing a melon will have a large depression. This allows dolphins to use echolocation for orientation. Though most dolphins do not have hair, they do have hair follicles that may perform some sensory function. Beyond locating an object, echolocation also provides the animal with an idea on an object's shape and size, though how exactly this works is not yet understood. The small hairs on the rostrum of the boto (river dolphins of South America) are believed to function as a tactile sense, possibly to compensate for the boto's poor eyesight.


title: Dolphin

text: The dolphin eye is relatively small for its size, yet they do retain a good degree of eyesight. As well as this, the eyes of a dolphin are placed on the sides of its head, so their vision consists of two fields, rather than a binocular view like humans have. When dolphins surface, their lens and cornea correct the nearsightedness that results from the water's refraction of light. Their eyes contain both rod and cone cells, meaning they can see in both dim and bright light, but they have far more rod cells than they do cone cells. They lack short wavelength sensitive visual pigments in their cone cells, indicating a more limited capacity for color vision than most mammals. Most dolphins have slightly flattened eyeballs, enlarged pupils (which shrink as they surface to prevent damage), slightly flattened corneas and a "tapetum lucidum" (eye tissue behind the retina); these adaptations allow for large amounts of light to pass through the eye and, therefore, a very clear image of the surrounding area. They also have glands on the eyelids and outer corneal layer that act as protection for the cornea.


title: Dolphin

text: Dolphins are not thought to have a good sense of taste, as their taste buds are atrophied or missing altogether. Some have preferences for different kinds of fish, indicating some ability to taste.


title: Dolphin

text: Dolphins are known to teach, learn, cooperate, scheme, and grieve. The neocortex of many species is home to elongated spindle neurons that, prior to 2007, were known only in hominids. In humans, these cells are involved in social conduct, emotions, judgment, and theory of mind. Cetacean spindle neurons are found in areas of the brain that are homologous to where they are found in humans, suggesting that they perform a similar function.


title: Dolphin

text: Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalization quotient that can be used as another indication of animal intelligence. Orcas have the second largest brain mass of any animal on earth, next to the sperm whale. The brain to body mass ratio in some is second only to humans.


title: Dolphin

text: Self-awareness is seen, by some, to be a sign of highly developed, abstract thinking. Self-awareness, though not well-defined scientifically, is believed to be the precursor to more advanced processes like meta-cognitive reasoning (thinking about thinking) that are typical of humans. Research in this field has suggested that cetaceans, among others, possess self-awareness.


title: Dolphin

text: The most widely used test for self-awareness in animals is the mirror test in which a mirror is introduced to an animal, and the animal is then marked with a temporary dye. If the animal then goes to the mirror in order to view the mark, it has exhibited strong evidence of self-awareness.


title: Dolphin

text: Some disagree with these findings, arguing that the results of these tests are open to human interpretation and susceptible to the Clever Hans effect. This test is much less definitive than when used for primates, because primates can touch the mark or the mirror, while cetaceans cannot, making their alleged self-recognition behavior less certain. Skeptics argue that behaviors that are said to identify self-awareness resemble existing social behaviors, and so researchers could be misinterpreting self-awareness for social responses to another individual. The researchers counter-argue that the behaviors shown are evidence of self-awareness, as they are very different from normal responses to another individual. Whereas apes can merely touch the mark on themselves with their fingers, cetaceans show less definitive behavior of self-awareness; they can only twist and turn themselves to observe the mark.


title: Dolphin

text: In 1995, Marten and Psarakos used television to test dolphin self-awareness. They showed dolphins real-time video of themselves, video of another dolphin and recorded footage. They concluded that their evidence suggested self-awareness rather than social behavior. While this particular study has not been repeated since then, dolphins have since passed the mirror test. Some researchers have argued that evidence for self-awareness has not been convincingly demonstrated.


title: Dolphin

text: Dolphins are highly social animals, often living in pods of up to a dozen individuals, though pod sizes and structures vary greatly between species and locations. In places with a high abundance of food, pods can merge temporarily, forming a "superpod"; such groupings may exceed 1,000 dolphins. Membership in pods is not rigid; interchange is common. They establish strong social bonds, and will stay with injured or ill members, helping them to breathe by bringing them to the surface if needed. This altruism does not appear to be limited to their own species. The dolphin "Moko" in New Zealand has been observed guiding a female pygmy sperm whale together with her calf out of shallow water where they had stranded several times. They have also been seen protecting swimmers from sharks by swimming circles around the swimmers or charging the sharks to make them go away.


title: Dolphin

text: Dolphins communicate using a variety of clicks, whistle-like sounds and other vocalizations. Dolphins also use nonverbal communication by means of touch and posturing.


title: Dolphin

text: Dolphins also display culture, something long believed to be unique to humans (and possibly other primate species). In May 2005, a discovery in Australia found Indo-Pacific bottlenose dolphins ("Tursiops aduncus") teaching their young to use tools. They cover their snouts with sponges to protect them while foraging. This knowledge is mostly transferred by mothers to daughters, unlike simian primates, where knowledge is generally passed on to both sexes. Using sponges as mouth protection is a learned behavior. Another learned behavior was discovered among river dolphins in Brazil, where some male dolphins use weeds and sticks as part of a sexual display.


title: Dolphin

text: Forms of care-giving between fellows and even for members of different species(see Moko (dolphin)) are recorded in various species – such as trying to save weakened fellows or female pilot whales holding up dead calves for long periods.


title: Dolphin

text: Dolphins engage in acts of aggression towards each other. The older a male dolphin is, the more likely his body is to be covered with bite scars. Male dolphins can get into disputes over companions and females. Acts of aggression can become so intense that targeted dolphins sometimes go into exile after losing a fight.


title: Dolphin

text: Male bottlenose dolphins have been known to engage in infanticide. Dolphins have also been known to kill porpoises for reasons which are not fully understood, as porpoises generally do not share the same diet as dolphins and are therefore not competitors for food supplies. The Cornwall Wildlife Trust records about one such death a year. Possible explanations include misdirected infanticide, misdirected sexual aggression or play behaviour.


title: Dolphin

text: Dolphin copulation happens belly to belly; though many species engage in lengthy foreplay, the actual act is usually brief, but may be repeated several times within a short timespan. The gestation period varies with species; for the small Tucuxi dolphin, this period is around 11 to 12 months, while for the orca, the gestation period is around 17 months. Typically dolphins give birth to a single calf, which is, unlike most other mammals, born tail first in most cases. They usually become sexually active at a young age, even before reaching sexual maturity. The age of sexual maturity varies by species and gender.


title: Dolphin

text: Dolphins are known to display non-reproductive sexual behavior, engaging in masturbation, stimulation of the genital area of other individuals using the rostrum or flippers, and homosexual contact.


title: Dolphin

text: Various species of dolphin have been known to engage in sexual behavior, including copulation with dolphins of other species, and occasionally exhibit behave sexually towards other animals, including humans. . Sexual encounters may be violent, with male dolphins sometimes showing aggressive behavior towards both females and other males. Male dolphins may also work together and attempt to herd females in estrus, keeping the females by their side by means of both physical aggression and intimidation, to increase their chances of reproductive success.


title: Dolphin

text: Generally, dolphins sleep with only one brain hemisphere in slow-wave sleep at a time, thus maintaining enough consciousness to breathe and to watch for possible predators and other threats. Sleep stages earlier in sleep can occur simultaneously in both hemispheres.


title: Dolphin

text: In captivity, dolphins seemingly enter a fully asleep state where both eyes are closed and there is no response to mild external stimuli. In this case, respiration is automatic; a tail kick reflex keeps the blowhole above the water if necessary. Anesthetized dolphins initially show a tail kick reflex. Though a similar state has been observed with wild sperm whales, it is not known if dolphins in the wild reach this state. The Indus river dolphin has a sleep method that is different from that of other dolphin species. Living in water with strong currents and potentially dangerous floating debris, it must swim continuously to avoid injury. As a result, this species sleeps in very short bursts which last between 4 and 60 seconds.


title: Dolphin

text: There are various feeding methods among and within species, some apparently exclusive to a single population. Fish and squid are the main food, but the false killer whale and the orca also feed on other marine mammals. Orcas on occasion also hunt whale species larger than themselves. Different breeds of dolphins vary widely in the number of teeth they possess. The orca usually carries 40–56 teeth while the popular bottlenose dolphin has anywhere from 72 to 116 conical teeth and its smaller cousin the common dolphin has 188–268 teeth: the number of teeth that an individual carries varies widely between within a single species. Hybrids between common and bottlenose bred in captivity had a nunmber of teeth intermediate between that of their parents.


title: Dolphin

text: One common feeding method is herding, where a pod squeezes a school of fish into a small volume, known as a bait ball. Individual members then take turns plowing through the ball, feeding on the stunned fish. Corralling is a method where dolphins chase fish into shallow water to catch them more easily. Orcas and bottlenose dolphins have also been known to drive their prey onto a beach to feed on it, a behaviour known as beach or strand feeding. Some species also whack fish with their flukes, stunning them and sometimes knocking them out of the water.


title: Dolphin

text: Reports of cooperative human-dolphin fishing date back to the ancient Roman author and natural philosopher Pliny the Elder. A modern human-dolphin partnership currently operates in Laguna, Santa Catarina, Brazil. Here, dolphins drive fish towards fishermen waiting along the shore and signal the men to cast their nets. The dolphins' reward is the fish that escape the nets.


title: Dolphin

text: In Shark Bay, Australia, dolphins catch fish by trapping them in huge conch shells. In "shelling", a dolphin brings the shell to the surface and shakes it, so that fish sheltering within fall into the dolphin's mouth. From 2007 to 2018, in 5,278 encounters with dolphins, researchers observed 19 dolphins shelling 42 times. The behavior spreads mainly within generations, rather than being passed from mother to offspring.


title: Dolphin

text: Dolphins are capable of making a broad range of sounds using nasal airsacs located just below the blowhole. Roughly three categories of sounds can be identified: frequency modulated whistles, burst-pulsed sounds, and clicks. Dolphins communicate with whistle-like sounds produced by vibrating connective tissue, similar to the way human vocal cords function, and through burst-pulsed sounds, though the nature and extent of that ability is not known. The clicks are directional and are for echolocation, often occurring in a short series called a click train. The click rate increases when approaching an object of interest. Dolphin echolocation clicks are amongst the loudest sounds made by marine animals.


title: Dolphin

text: Bottlenose dolphins have been found to have signature whistles, a whistle that is unique to a specific individual. These whistles are used in order for dolphins to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of a name for humans. These signature whistles are developed during a dolphin's first year; it continues to maintain the same sound throughout its lifetime. In order to obtain each individual whistle sound, dolphins undergo vocal production learning. This consists of an experience with other dolphins that modifies the signal structure of an existing whistle sound. An auditory experience influences the whistle development of each dolphin. Dolphins are able to communicate to one another by addressing another dolphin through mimicking their whistle. The signature whistle of a male bottlenose dolphin tends to be similar to that of his mother, while the signature whistle of a female bottlenose dolphin tends to be more distinguishing. Bottlenose dolphins have a strong memory when it comes to these signature whistles, as they are able to relate to a signature whistle of an individual they have not encountered for over twenty years. Research done on signature whistle usage by other dolphin species is relatively limited. The research on other species done so far has yielded varied outcomes and inconclusive results.


title: Dolphin

text: Because dolphins are generally associated in groups, communication is necessary. Signal masking is when other similar sounds (conspecific sounds) interfere with the original acoustic sound. In larger groups, individual whistle sounds are less prominent. Dolphins tend to travel in pods, upon which there are groups of dolphins that range from a few to many. Although they are traveling in these pods, the dolphins do not necessarily swim right next to each other. Rather, they swim within the same general vicinity. In order to prevent losing one of their pod members, there are higher whistle rates. Because their group members were spread out, this was done in order to continue traveling together.


title: Dolphin

text: Dolphins frequently leap above the water surface, this being done for various reasons. When travelling, jumping can save the dolphin energy as there is less friction while in the air. This type of travel is known as porpoising. Other reasons include orientation, social displays, fighting, non-verbal communication, entertainment and attempting to dislodge parasites.


title: Dolphin

text: Dolphins show various types of playful behavior, often including objects, self-made bubble rings, other dolphins or other animals. When playing with objects or small animals, common behavior includes carrying the object or animal along using various parts of the body, passing it along to other members of the group or taking it from another member, or throwing it out of the water. Dolphins have also been observed harassing animals in other ways, for example by dragging birds underwater without showing any intent to eat them. Playful behaviour that involves another animal species with active participation of the other animal has also been observed. Playful dolphin interactions with humans are the most obvious examples, followed by those with humpback whales and dogs.


title: Dolphin

text: Juvenile dolphins off the coast of Western Australi have been observed chasing, capturing, and chewing on blowfish. While some reports state that the dolphins are becoming intoxicated on the tetrodotoxin in the fishes' skin, other reports have characterized this behavior as the normal curiosity and exploration of their environment in which dolphins engage.


title: Dolphin

text: Although this behaviour is highly unusual in wild dolphins, several Indo-Pacific bottlenose dolphins ("Tursiops aduncus") of the Port River, north of Adelaide, South Australia, have been seen to have exhibit "tail-walking". This activity mimicks a standing posture, using the tail to run backwards along the water. To perform this movement, the dolphin "forces the majority of its body vertically out of the water and maintains the position by vigorously pumping its tail".


title: Dolphin

text: This started in 1988 when a female named Billie was rescued after becoming trapped in a polluted marina, and spent two weeks recuperating with captive dolphins. Billie had previously been observed swimming and frolicking with racehorses exercising in the Port River in the 1980s. After becoming trapped in a reedy estuary further down the coast, she was rescued and placed with several captive dolphins at a marine park to recuperate. There she observed the captive dolphins performing tail-walking. After being returned to the Port River, she continued to perform this trick, and another dolphin, Wave, copied her. Wave, a very active tail-walker, passed on the skill to her daughters, Ripple and Tallula.


title: Dolphin

text: After Billie's premature death, Wave started tail-walking much more frequently, and other dolphins in the group were observed also performing the behaviour. In 2011, up to 12 dolphins were observed tail-walking, but only females appeared to learn the skill. In October 2021, a dolphin was observed tail-walking over a number of hours.


title: Dolphin

text: Scientists have found the spread of this behaviour, through up to two generations, surprising, as it brings no apparent advantage, and is very energy-consuming. A 2018 study by Mike Rossley et al. suggested:


title: Dolphin

text: Dolphins have few marine enemies. Some species or specific populations have none, making them apex predators. For most of the smaller species of dolphins, only a few of the larger sharks, such as the bull shark, dusky shark, tiger shark and great white shark, are a potential risk, especially for calves. Some of the larger dolphin species, especially orcas, may also prey on smaller dolphins, but this seems rare. Dolphins also suffer from a wide variety of diseases and parasites. The Cetacean morbillivirus in particular has been known to cause regional epizootics often leaving hundreds of animals of various species dead. Symptoms of infection are often a severe combination of pneumonia, encephalitis and damage to the immune system, which greatly impair the cetacean's ability to swim and stay afloat unassisted. A study at the U.S. National Marine Mammal Foundation revealed that dolphins, like humans, develop a natural form of type 2 diabetes which may lead to a better understanding of the disease and new treatments for both humans and dolphins.


title: Dolphin

text: Dolphins can tolerate and recover from extreme injuries such as shark bites although the exact methods used to achieve this are not known. The healing process is rapid and even very deep wounds do not cause dolphins to hemorrhage to death. Furthermore, even gaping wounds restore in such a way that the animal's body shape is restored, and infection of such large wounds seems rare.


title: Dolphin

text: A study published in the journal "Marine Mammal Science" suggests that at least some dolphins survive shark attacks using everything from sophisticated combat moves to teaming up against the shark.


title: Dolphin

text: Some dolphin species are at risk of extinction, especially some river dolphin species such as the Amazon river dolphin, and the Ganges and Yangtze river dolphin, which are critically or seriously endangered. A 2006 survey found no individuals of the Yangtze river dolphin. The species now appears to be functionally extinct.


title: Dolphin

text: Pesticides, heavy metals, plastics, and other industrial and agricultural pollutants that do not disintegrate rapidly in the environment concentrate in predators such as dolphins. Injuries or deaths due to collisions with boats, especially their propellers, are also common.


title: Dolphin

text: Various fishing methods, most notably purse seine fishing for tuna and the use of drift and gill nets, unintentionally kill many dolphins. Accidental by-catch in gill nets and incidental captures in antipredator nets that protect marine fish farms are common and pose a risk for mainly local dolphin populations. In some parts of the world, such as Taiji in Japan and the Faroe Islands, dolphins are traditionally considered food and are killed in harpoon or drive hunts. Dolphin meat is high in mercury and may thus pose a health danger to humans when consumed.


title: Dolphin

text: Queensland's shark culling program, which has killed roughly 50,000 sharks since 1962, has also killed thousands of dolphins as bycatch. "Shark control" programs in both Queensland and New South Wales use shark nets and drum lines, which entangle and kill dolphins. Queensland's "shark control" program has killed more than 1,000 dolphins in recent years, and at least 32 dolphins have been killed in Queensland since 2014. A shark culling program in KwaZulu-Natal has killed at least 2,310 dolphins.


title: Dolphin

text: Dolphin safe labels attempt to reassure consumers that fish and other marine products have been caught in a dolphin-friendly way. The earliest campaigns with "dolphin safe" labels were initiated in the 1980s as a result of cooperation between marine activists and the major tuna companies, and involved decreasing incidental dolphin kills by up to 50% by changing the type of nets used to catch tuna. The dolphins are netted only while fishermen are in pursuit of smaller tuna. Albacore are not netted this way, making albacore the only truly dolphin-safe tuna.


title: Dolphin

text: Loud underwater noises, such as those resulting from naval sonar use, live firing exercises, and certain offshore construction projects such as wind farms, may be harmful to dolphins, increasing stress, damaging hearing, and causing decompression sickness by forcing them to surface too quickly to escape the noise.


title: Dolphin

text: Dolphins and other smaller cetaceans are also hunted in an activity known as dolphin drive hunting. This is accomplished by driving a pod together with boats and usually into a bay or onto a beach. Their escape is prevented by closing off the route to the ocean with other boats or nets. Dolphins are hunted this way in several places around the world, including the Solomon Islands, the Faroe Islands, Peru, and Japan, the most well-known practitioner of this method. By numbers, dolphins are mostly hunted for their meat, though some end up in dolphinariums. Despite the controversial nature of the hunt resulting in international criticism, and the possible health risk that the often polluted meat causes, thousands of dolphins are caught in drive hunts each year.


title: Dolphin

text: Dolphins are marine mammals with broad geographic extent, making them susceptible to climate change in various ways. The most common effect of climate change on dolphins is the increasing water temperatures across the globe. This has caused a large variety of dolphin species to experience range shifts, in which the species move from their typical geographic region to cooler waters. Another side effect of increasing water temperatures is the increase in harmful algae blooms, which has caused a mass die-off of bottlenose dolphins.


title: Dolphin

text: In California, the 1982-83 El Niño warming event caused the near-bottom spawning market squid to leave southern California, which caused their predator, the pilot whale, to also leave. As the market squid returned six years later, Risso's dolphins came to feed on the squid. Bottlenose dolphins expanded their range from southern to central California, and stayed even after the warming event subsided. The Pacific white-sided dolphin has had a decline in population in the southwest Gulf of California, the southern boundary of their distribution. In the 1980s they were abundant with group sizes up to 200 across the entire cool season. Then, in the 2000s, only two groups were recorded with sizes of 20 and 30, and only across the central cool season. This decline was not related to a decline of other marine mammals or prey, so it was concluded to have been caused by climate change as it occurred during a period of warming. Additionally, the Pacific white-sided dolphin had an increase in occurrence on the west coast of Canada from 1984 to 1998.


title: Dolphin

text: In the Mediterranean, sea surface temperatures have increased, as well as salinity, upwelling intensity, and sea levels. Because of this, prey resources have been reduced causing a steep decline in the short-beaked common dolphin Mediterranean subpopulation, which was deemed endangered in 2003. This species now only exists in the Alboran Sea, due to its high productivity, distinct ecosystem, and differing conditions from the rest of the Mediterranean.


title: Dolphin

text: In northwest Europe, many dolphin species have experienced range shifts from the region's typically colder waters. Warm water dolphins, like the short-beaked common dolphin and striped dolphin, have expanded north of western Britain and into the northern North Sea, even in the winter, which may displace the white-beaked and Atlantic white-sided dolphin that are in that region. The white-beaked dolphin has shown an increase in the southern North Sea since the 1960s because of this. The rough-toothed dolphin and Atlantic spotted dolphin may move to northwest Europe. In northwest Scotland, white-beaked dolphins (local to the colder waters of the North Atlantic) have decreased while common dolphins (local to warmer waters) have increased from 1992 to 2003. Additionally, Fraser's dolphin, found in tropical waters, was recorded in the UK for the first time in 1996.


title: Dolphin

text: River dolphins are highly affected by climate change as high evaporation rates, increased water temperatures, decreased precipitation, and increased acidification occur. River dolphins typically have a higher densities when rivers have a lox index of freshwater degradation and better water quality. Specifically looking at the Ganges river dolphin, the high evaporation rates and increased flooding on the plains may lead to more human river regulation, decreasing the dolphin population.


title: Dolphin

text: As warmer waters lead to a decrease in dolphin prey, this led to other causes of dolphin population decrease. In the case of bottlenose dolphins, mullet populations decrease due to increasing water temperatures, which leads to a decrease in the dolphins' health and thus their population. At the Shark Bay World Heritage Area in Western Australia, the local Indo-Pacific bottlenose dolphin population had a significant decline after a marine heatwave in 2011. This heatwave caused a decrease in prey, which led to a decline in dolphin reproductive rates as female dolphins could not get enough nutrients to sustain a calf. The resultant decrease in fish population due to warming waters has also influenced humans to see dolphins as fishing competitors or even bait. Humans use dusky dolphins as bait or are killed off because they consume the same fish humans eat and sell for profit. In the central Brazilian Amazon alone, approximately 600 pink river dolphins are killed each year to be used as bait.


title: Dolphin

text: In Greek myths, dolphins were seen invariably as helpers of humankind. Dolphins also seem to have been important to the Minoans, judging by artistic evidence from the ruined palace at Knossos. During the 2009 excavations of a major Mycenaean city at Iklaina, a striking fragment of a wall-paintings came to light, depicting a ship with three human figures and dolphins. Dolphins are common in Greek mythology, and many coins from ancient Greece have been found which feature a man, a boy or a deity riding on the back of a dolphin. The Ancient Greeks welcomed dolphins; spotting dolphins riding in a ship's wake was considered a good omen. In both ancient and later art, Cupid is often shown riding a dolphin. A dolphin rescued the poet Arion from drowning and carried him safe to land, at Cape Matapan, a promontory forming the southernmost point of the Peloponnesus. There was a temple to Poseidon and a statue of Arion riding the dolphin.


title: Dolphin

text: The Greeks reimagined the Phoenician god Melqart as Melikertês (Melicertes) and made him the son of Athamas and Ino. He drowned but was transfigured as the marine deity Palaemon, while his mother became Leucothea. ("cf" Ino.) At Corinth, he was so closely connected with the cult of Poseidon that the Isthmian Games, originally instituted in Poseidon's honor, came to be looked upon as the funeral games of Melicertes. Phalanthus was another legendary character brought safely to shore (in Italy) on the back of a dolphin, according to Pausanias.


title: Dolphin

text: Dionysus was once captured by Etruscan pirates who mistook him for a wealthy prince they could ransom. After the ship set sail Dionysus invoked his divine powers, causing vines to overgrow the ship where the mast and sails had been. He turned the oars into serpents, so terrifying the sailors that they jumped overboard, but Dionysus took pity on them and transformed them into dolphins so that they would spend their lives providing help for those in need. Dolphins were also the messengers of Poseidon and sometimes did errands for him as well. Dolphins were sacred to both Aphrodite and Apollo.


title: Dolphin

text: "Dolfin" was the name of an aristocratic family in the maritime Republic of Venice, whose most prominent member was the 13th-century Doge Giovanni Dolfin.


title: Dolphin

text: In Hindu mythology the Ganges river dolphin is associated with Ganga, the deity of the Ganges river. The dolphin is said to be among the creatures which heralded the goddess' descent from the heavens and her mount, the Makara, is sometimes depicted as a dolphin.


title: Dolphin

text: The Boto, a species of river dolphin that resides in the Amazon River, are believed to be shapeshifters, or "encantados", who are capable of having children with human women.


title: Dolphin

text: There are comparatively few surviving myths of dolphins in Polynesian cultures, in spite of their maritime traditions and relevance of other marine animals such as sharks and seabirds; unlike these, they are more often perceived as food than as totemic symbols. Dolphins are most clearly represented in Rapa Nui Rongorongo, and in the traditions of the Caroline Islands they are depicted similarly to the Boto, being sexually active shapeshifters.


title: Dolphin

text: Dolphins are also used as symbols, for instance in heraldry. When heraldry developed in the Middle Ages, little was known about the biology of the dolphin and it was often depicted as a sort of fish. The stylised heraldic dolphin still conventionally follows this tradition, sometimes showing the dolphin skin covered with fish scales.


title: Dolphin

text: A well-known historical example was the coat of arms of the former province of the Dauphiné in southern France, from which were derived the arms and the title of the Dauphin of France, the heir to the former throne of France (the title literally meaning "The Dolphin of France").


title: Dolphin

text: Dolphins are present in the coat of arms of Anguilla and the coat of arms of Romania, and the coat of arms of Barbados has a dolphin supporter.


title: Dolphin

text: The coat of arms of the town of Poole, Dorset, England, first recorded in 1563, includes a dolphin, which was historically depicted in stylised heraldic form, but which since 1976 has been depicted naturalistically.


title: Dolphin

text: The renewed popularity of dolphins in the 1960s resulted in the appearance of many dolphinaria around the world, making dolphins accessible to the public. Criticism and animal welfare laws forced many to close, although hundreds still exist around the world. In the United States, the best known are the SeaWorld marine mammal parks.


title: Dolphin

text: Various species of dolphins are kept in captivity. These small cetaceans are more often than not kept in theme parks, such as SeaWorld, commonly known as a dolphinarium. Bottlenose dolphins are the most common species of dolphin kept in dolphinariums as they are relatively easy to train, have a long lifespan in captivity and have a friendly appearance. Hundreds if not thousands of bottlenose dolphins live in captivity across the world, though exact numbers are hard to determine. Other species kept in captivity are spotted dolphins, false killer whales and common dolphins, Commerson's dolphins, as well as rough-toothed dolphins, but all in much lower numbers than the bottlenose dolphin. There are also fewer than ten pilot whales, Amazon river dolphins, Risso's dolphins, spinner dolphins, or tucuxi in captivity. An unusual and very rare hybrid dolphin, known as a wolphin, is kept at the Sea Life Park in Hawaii, which is a cross between a bottlenose dolphin and a false killer whale.


title: Dolphin

text: The number of orcas kept in captivity is very small, especially when compared to the number of bottlenose dolphins, with 60 captive orcas being held in aquaria . The orca's intelligence, trainability, striking appearance, playfulness in captivity and sheer size have made it a popular exhibit at aquaria and aquatic theme parks. From 1976 to 1997, 55 whales were taken from the wild in Iceland, 19 from Japan, and three from Argentina. These figures exclude animals that died during capture. Live captures fell dramatically in the 1990s, and by 1999, about 40% of the 48 animals on display in the world were captive-born.


title: Dolphin

text: Organizations such as the Mote Marine Laboratory rescue and rehabilitate sick, wounded, stranded or orphaned dolphins while others, such as the Whale and Dolphin Conservation and Hong Kong Dolphin Conservation Society, work on dolphin conservation and welfare. India has declared the dolphin as its national aquatic animal in an attempt to protect the endangered Ganges river dolphin. The Vikramshila Gangetic Dolphin Sanctuary has been created in the Ganges river for the protection of the animals.