Observational history.

Discovery and naming.

There is no reliable evidence of Eta Carinae being observed or recorded before the 17th century, although Dutch navigator Pieter Keyser described a fourth-magnitude star at approximately the correct position around 1595–1596, which was copied onto the celestial globes of Petrus Plancius and Jodocus Hondius and the 1603 "Uranometria" of Johann Bayer. Frederick de Houtman's independent star catalogue from 1603 does not include Eta Carinae among the other 4th magnitude stars in the region. The earliest firm record was made by Edmond Halley in 1677 when he recorded the star simply as "Sequens" (i.e. "following" relative to another star) within a new constellation Robur Carolinum. His "Catalogus Stellarum Australium" was published in 1679. The star was also known by the Bayer designations Eta Roboris Caroli, Eta Argus or Eta Navis. In 1751 Nicolas Louis de Lacaille gave the stars of Argo Navis and Robur Carolinum a single set of Greek letter Bayer designations within his constellation Argo, and designated three areas within Argo for

Great Eruption.

In 1827 Burchell specifically noted Eta Carinae's unusual brightness at 1st magnitude, and was the first to suspect that it varied in brightness. John Herschel, who was in South Africa at the time, made a detailed series of accurate measurements in the 1830s showing that Eta Carinae consistently shone around magnitude 1.4 until November 1837. On the evening of December 16, 1837, Herschel was astonished to see that it had brightened to slightly outshine Rigel. This event marked the beginning of a roughly 18-year period known as the Great Eruption.  Eta Carinae was brighter still on January 2, 1838, equivalent to Alpha Centauri, before fading slightly over the following three months. Herschel did not observe the star after this, but received correspondence from the Reverend W.S. Mackay in Calcutta, who wrote in 1843, "To my great surprise I observed this March last (1843), that the star Eta Argus had become a star of the first magnitude fully as bright as Canopus, and

Lesser Eruption.

A new brightening started in 1887, peaked at about magnitude 6.2 in 1892, then at the end of March 1895 faded rapidly to about magnitude 7.5. Although there are only visual records of the 1890 eruption,

Twentieth century.

Between 1900 and at least 1940, Eta Carinae appeared to have settled at a constant brightness at around magnitude 7.6, but in 1953 it was noted to have brightened again to magnitude 6.5. The brightening continued steadily, but with fairly regular variations of a few tenths of a magnitude. In 1996 the variations were first identified as having a 5.52-year period, later measured more accurately at 5.54 years, leading to the idea of a binary system. The binary theory was confirmed by observations of radio, optical, and near infrared radial velocity and line profile changes, referred to collectively as a "spectroscopic event", at the predicted time of periastron passage in late 1997 and early 1998. At the same time there was a complete collapse of the X-ray emission presumed to originate

Visibility.

As a 4th-magnitude star, Eta Carinae is comfortably visible to the naked eye in all but the most light-polluted skies in inner city areas according to the Bortle scale. Its brightness has varied over a wide range, from the second-brightest star in the sky at one point in the 19th century to well below naked eye visibility. Its location at around 60°S in the far Southern Celestial Hemisphere means it cannot be seen by observers in Europe and much of North America.  Located between Canopus and the Southern Cross, Eta Carinae is easily pinpointed as the brightest star within the large naked eye Carina Nebula. In a telescope the "star" is framed within the dark "V" dust lane of the nebula and appears distinctly orange and clearly non-stellar. High magnification will show the two orange lobes of a surrounding reflection nebula known as the Homunculus Nebula on either side of a bright central core. Variable star observers can compare its brightness with several 4th- and 5th-magnitude stars closely surrounding the nebula.  Discovered in 1961, the weak Eta Carinids meteor shower has a radiant very close to Eta Carinae. Occurring from 14 to 28 January, the shower peaks around 21 January. Meteor showers are not associated with bodies outside the Solar System, making the proximity to Eta Carinae merely a coincidence.

Visual spectrum.

The strength and profile of the lines in the Eta Carinae spectrum are highly variable, but there are a number of consistent distinctive features. The spectrum is dominated by emission lines, usually broad although the higher excitation lines are overlaid by a narrow central component from dense ionised nebulosity, especially the Weigelt Blobs. Most lines show a P Cygni profile but with the absorption wing much weaker than the emission. The broad P Cygni lines are typical of strong stellar winds, with very weak absorption in this case because the central star is so heavily obscured. Electron scattering wings are present but relatively weak, indicating a clumpy wind. Hydrogen lines are present and strong, showing that Eta Carinae still retains much of its hydrogen envelope. He lines are much weaker than

Ultraviolet.

The ultraviolet spectrum of the Eta Carinae system shows many emission lines of ionised metals such as Fe and Cr, as well as Lyman (Ly) and a continuum from a hot central source. The ionisation levels and continuum require the existence of a source with a temperature at least 37,000 K.  Certain Fe UV lines are unusually strong. These originate in the Weigelt Blobs and are caused by a low-gain lasing effect. Ionised hydrogen between a blob and the central star generates intense Ly emission

Infrared.

Infrared observations of Eta Carinae have become increasingly important. The vast majority of the electromagnetic radiation from the central stars is absorbed by surrounding dust, then emitted as mid- and far infrared appropriate to the temperature of the dust. This allows almost the entire energy output of the system to be observed at wavelengths that are not strongly affected by interstellar extinction, leading to estimates of the luminosity that are more accurate than for other extremely luminous stars. Eta Carinae

High energy radiation.

Several X-ray and gamma-ray sources have been detected around Eta Carinae, for example 4U 1037–60 in the 4th Uhuru catalogue and 1044–59 in the HEAO-2 catalog. The earliest detection of X-rays in the Eta Carinae region was from the Terrier-Sandhawk rocket, followed by Ariel 5, OSO 8, and Uhuru sightings.  More detailed observations were made with the Einstein Observatory, ROSAT X-ray telescope, Advanced Satellite for Cosmology and Astrophysics (ASCA), and Chandra X-ray Observatory. There are multiple sources at various wavelengths right across the high energy

Radio emission.

Radio emissions have been observed from Eta Carinae across the microwave band. It has been detected in the 21 cm H line, but has been particularly closely studied in the millimetre and centimetre bands. Masing hydrogen recombination lines (from the combining of an electron and proton to form a hydrogen atom) have been detected in this range. The emission is concentrated in a small non-point source less than 4 arcseconds across and appears to be

Surroundings.

Eta Carinae is found within the Carina Nebula, a giant star-forming region in the Carina–Sagittarius Arm of the Milky Way. The nebula is a prominent naked eye object in the southern skies showing a complex mix of emission, reflection, and dark nebulosity. Eta Carinae is known to be at the same distance as the Carina Nebula and its spectrum can be seen reflected off various star clouds in the nebula. The appearance of the Carina Nebula, and particularly of the Keyhole region, has changed significantly since it was described by John Herschel over years ago. This is thought to be due to the reduction in ionising radiation from Eta Carinae since the Great Eruption. Prior to the Great Eruption the Eta Carinae system contributed up to 20% of the total ionizing flux for the whole Carina Nebula, but that is now mostly blocked by the surrounding gas and dust.

Trumpler 16.

Eta Carinae lies within the scattered stars of the Trumpler 16 open cluster. All the other members are well below naked eye visibility, although WR

Homunculus.

Eta Carinae is enclosed by, and lights up, the Homunculus Nebula, a small emission and reflection nebula composed mainly of gas ejected during the Great Eruption event in the mid-19th century, as well as dust that condensed from the debris. The nebula consists of two polar lobes aligned with the rotation axis of the star, plus an equatorial "skirt", the whole being around long. Closer studies show many fine details: a "Little Homunculus" within the main nebula, probably formed by the 1890 eruption; a jet; fine streams and knots of material, especially noticeable in the skirt region; and three Weigelt Blobs—dense gas condensations very close to the star itself.  The lobes of the Homunculus are considered to be formed almost entirely due to the initial eruption, rather than shaped by or including previously ejected or interstellar material,

Distance.

The distance to Eta Carinae has been determined by several different methods, resulting in a widely accepted value of 2,300 parsecs (7,800 light-years), with a margin of error around 100 parsecs (330 light-years). The distance to Eta Carinae itself cannot be measured using parallax due to its surrounding nebulosity, but other stars in the Trumpler 16 cluster are expected to be at a similar distance and are accessible to parallax. Gaia Data Release 2 has provided the parallax for many stars considered to be members of Trumpler 16, finding that the four hottest O-class stars in the region have very similar parallaxes with a mean value of 0.383 ± 0.017 milli-arcseconds (mas), which translates to a distance of 2,600 ± 100 parsecs. This implies that Eta Carinae may be more distant than previously thought, and also more

Properties.

The Eta Carinae star system is currently one of the most massive stars that can be studied in great detail. Until recently Eta Carinae was thought to be the most massive single star, but the system's binary nature was proposed by the Brazilian astronomer Augusto Damineli in 1996 and confirmed in 2005. Both component stars are largely obscured by circumstellar material ejected from Eta Carinae A, and basic properties such as their temperatures and luminosities can only be inferred. Rapid changes to the stellar wind in the 21st century suggest that the star itself may be revealed when dust from the great eruption finally clears.

Orbit.

The binary nature of Eta Carinae is clearly established, although the components have not been directly observed and cannot even be clearly resolved spectroscopically due to scattering and re-excitation in the surrounding nebulosity. Periodic photometric and spectroscopic variations prompted the search for a companion, and modelling of the colliding winds and partial "eclipses" of some spectroscopic features have constrained the possible orbits.  The period of the orbit is accurately known at 5.539 years, although this has changed over time due to mass loss and accretion. The period between the Great Eruption and the smaller 1890 eruption was apparently 5.52 years,

Classification.

Eta Carinae A is classified as a luminous blue variable (LBV) due to the distinctive spectral and brightness variations. This type of variable star is characterised by irregular changes from a high temperature quiescent state to a low temperature outburst state at roughly constant luminosity. LBVs in the quiescent state lie on a narrow S Doradus instability strip, with more luminous stars being hotter. In outburst all LBVs have about the same temperature, which is near 8,000 K. LBVs in a normal outburst are visually brighter than when quiescent although the bolometric luminosity is unchanged.  A Great Eruption event similar to Eta Carinae A's has only been observed in one other star in the Milky Way—P Cygni—and in a handful of other possible LBVs in external galaxies. None of them seem to be quite as violent as Eta Carinae's. It is unclear if this is something that only a very few of the most massive LBVs undergo, something

Mass.

The masses of stars are difficult to measure except by determination of a binary orbit. Eta Carinae is a binary system, but certain key information about the orbit is not known accurately. The mass can be strongly constrained to be greater than, due to the high luminosity. Standard models of the system assume masses of

Mass loss.

Mass loss is one of the most intensively studied aspects of massive star research. Put simply, calculated mass loss rates in the best models of stellar evolution do not reproduce the observed properties of evolved massive stars such as Wolf–Rayets, the number and types of core collapse supernovae, or their progenitors. To match those observations, the models require much higher mass loss rates. Eta Carinae A has one of the highest known mass loss rates, currently around /year, and is an obvious candidate for study.  Eta Carinae A is losing a lot of mass due to its extreme luminosity and relatively low surface gravity. Its stellar wind is entirely opaque and appears as a pseudo-photosphere; this optically dense surface hides the true physical surface of the star. During the

Luminosity.

The stars of the Eta Carinae system are completely obscured by dust and opaque stellar winds, with much of the ultraviolet and visual radiation shifted to infrared. The total electromagnetic radiation across all wavelengths for both stars combined is several million solar luminosities (). The best estimate for the luminosity of the primary is making it one of the most luminous stars in the Milky Way. The luminosity of Eta Carinae B is particularly uncertain, probably and almost certainly no more than.  The most notable feature of Eta Carinae is its giant eruption or supernova impostor event, which originated in the primary star

Temperature.

Until late in the 20th century, the temperature of Eta Carinae was assumed to be over 30,000 K because of the presence of high excitation spectral lines, but other aspects of the spectrum suggested much lower temperatures and complex models were created to account for this. It is now known that the Eta Carinae system consists of at least two stars, both with strong stellar winds and a shocked colliding wind (wind-wind collision or WWC) zone, embedded within a dusty nebula that reprocesses 90% of the electromagnetic

Size.

The size of the two main stars in the Eta Carinae system is difficult to determine precisely because neither star can be seen directly. Eta Carinae B is likely to have a well-defined photosphere and its radius can be estimated from the assumed type of star. An O supergiant of with a temperature of 37,200 K has an effective radius of.  The size of Eta Carinae A is not even well defined. It has an optically dense stellar wind so the typical definition of a star's surface being approximately where it becomes opaque gives a very different result to where a more traditional definition of a surface might be. One study calculated a radius of for

Rotation.

Rotation rates of massive stars have a critical influence on their evolution and eventual death. The rotation rate of the Eta Carinae stars cannot be measured directly because their surfaces cannot be seen. Single massive stars

Eruptions.

Two eruptions have been observed from Eta Carinae, the Great Eruption of the mid 19th century and the Lesser Eruption of 1890. In addition, studies of outlying nebulosity suggest at least one earlier eruption around AD 1250. A further eruption may have occurred around AD 1550, although it is possible that the material indicating this eruption is actually from the Great Eruption slowed down by colliding with older nebulosity. The mechanism producing these eruptions is unknown. It is not even clear whether the eruptions involve explosive events or so-called super-Eddington winds, an extreme form of stellar wind involving very high mass loss induced by an increase in the luminosity of the star.

Evolution.

Eta Carinae is a unique object, with no very close analogues currently known in any galaxy. Therefore, its future evolution is highly uncertain, but almost certainly involves further mass loss and an eventual supernova.  Eta Carinae A would have begun life as an extremely hot star on the main sequence, already a highly luminous object over. The exact properties would depend on the initial mass, which is expected to have been at least and possibly much higher. A typical spectrum when first formed would be O2If and the star would be mostly or fully convective due to CNO cycle fusion at the very high core temperatures. Sufficiently massive or differentially rotating stars undergo such strong mixing that they remain chemically homogeneous during core hydrogen burning.  As core hydrogen burning progresses, a very massive star would slowly expand and become more luminous, becoming a blue hypergiant and eventually an LBV while still fusing hydrogen in the core. When hydrogen at the core is depleted after 2–2.5 million years, hydrogen shell burning continues with further increases in size and luminosity, although hydrogen shell burning in chemically homogeneous stars may be very brief or absent since the entire star would become depleted of hydrogen. In the late stages of hydrogen burning, mass loss is extremely high due to the high luminosity and enhanced surface abundances of helium and nitrogen. As hydrogen burning ends and core helium burning begins, massive stars transition very rapidly to the Wolf–Rayet stage with little or no hydrogen, increased temperatures, and decreased luminosity. They are likely to have lost over half their initial mass at this point.  It is unclear whether triple-alpha helium fusion has started at the core of Eta Carinae A. The elemental abundances at the surface cannot be accurately measured, but ejecta within the Homunculus are around 60% hydrogen and 40% helium, with nitrogen enhanced to ten times solar levels. This is indicative of ongoing CNO cycle hydrogen fusion.  Models of the evolution and death of single very massive stars predict an increase in temperature during helium core burning, with the outer layers of the star being lost. It becomes a Wolf–Rayet star on the nitrogen sequence, moving from WNL to WNE as more of the outer layers are lost, possibly reaching the WC or WO spectral class as carbon and oxygen from the triple alpha process reach the surface. This process would continue with heavier elements being fused until an iron core develops, at which point the core collapses and the star is destroyed. Subtle differences in initial conditions, in the models themselves, and most especially in the rates of mass loss, produce different predictions for the final state of the most massive stars. They may survive to become a helium-stripped star or they may collapse at an earlier stage while they retain more of their outer layers. The lack of sufficiently luminous WN stars and the discovery of apparent LBV supernova progenitors has also prompted the suggestion that certain types of LBVs explode as a supernova without evolving further.  Eta Carinae is a close binary and this complicates the evolution of both stars. Compact massive companions can strip mass from larger primary stars much more quickly than would occur in a single star, so the properties at core collapse can be very different. In some scenarios, the secondary can accrue significant mass, accelerating its evolution, and in turn be stripped by the now compact Wolf–Rayet primary. In the case of Eta Carinae, the secondary is clearly causing additional instability in the primary, making it difficult to predict future developments.

Potential supernova.

The overwhelming probability is that the next supernova observed in the Milky Way will originate from an unknown white dwarf or anonymous red supergiant, very likely not even visible to the naked eye. Nevertheless, the prospect of a supernova originating from an object as extreme, nearby, and well-studied as Eta Carinae arouses great interest.  As a single star, a star originally around 150 times as massive as the Sun would typically reach core collapse as a Wolf–Rayet star within 3 million years. At low metallicity, many massive stars will collapse directly to a black hole with no visible explosion or a sub-luminous supernova, and a small fraction will produce a pair-instability supernova, but at solar metallicity and above there is expected to be sufficient mass loss before collapse to allow a visible supernova of type Ib or Ic. If there is still a large amount of expelled material close to the star, the shock formed by the supernova explosion impacting the circumstellar material can efficiently convert kinetic energy to radiation, resulting in a superluminous supernova (SLSN) or hypernova, several

Possible effects on Earth.

A typical core collapse supernova at the distance of Eta Carinae would peak at an apparent magnitude around −4, similar to Venus. A SLSN could be five magnitudes brighter, potentially the brightest supernova in recorded history (currently SN 1006). At 7,500 light-years from the star it is unlikely to directly affect terrestrial lifeforms, as they will be protected from gamma rays by the atmosphere and from some other cosmic rays by the magnetosphere. The main damage would be restricted to the upper atmosphere, the ozone layer, spacecraft, including satellites, and any astronauts in space. At least one paper has projected that complete loss of the Earth's ozone layer is a plausible consequence of a supernova, which would result in a significant increase in UV

Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around 7,500 light-years (2,300 parsecs) distant in the constellation Carina. Previously a 4th-magnitude star, it brightened in 1837 to become brighter than Rigel, marking the start of its so-called "Great Eruption". It became the second-brightest star in the sky between 11 and 14 March 1843 before fading well below naked eye visibility after 1856. In a smaller eruption, it reached 6th magnitude in 1892 before fading again. It has brightened consistently since about 1940, becoming brighter than magnitude 4.5 by 2014.

海山二(Eta Carinae)是位于船底座的一个恒星系统(赤经10 h 45.1 m、赤纬−59°41m),距离太阳7,500至8,000光年,在北纬27°以北的地区难以看见,而在南纬30°是一颗拱极星。这个系统至少有两颗恒星,其中一颗是位于恒星生命早期阶段,质量大约是太阳150倍的高光度蓝变星(LBV),并且至少已经流失30个太阳质量。虽然它被认为还有一颗较大的伴星,质量约为太阳30倍的沃夫–瑞叶星环绕着它,但海山二周围有巨大厚重的红色星云,因而很难直接的发现。它总体的光度大约是太阳的590万倍,而系统的质量估计超过150倍太阳质量 。由于它的质量和生命阶段,预期在天文学上不久的将来,它将爆炸成为一颗极超新星,目前的估计是从现在开始的10,000年至20,000年。


Etymology and pluralisation.

The scientific Latin term "octopus" was derived from Ancient Greek ὀκτώπους, a compound form of ὀκτώ ("oktō", "eight") and πούς ("pous", "foot"), itself a variant form of ὀκτάπους, a word used for example by Alexander of Tralles (c. 525–605) for the common octopus. The standard pluralised form of "octopus" in English is "octopuses"; the Ancient Greek plural ὀκτώποδες, "octopodes" (), has also been used historically. The alternative plural "octopi" is considered grammatically incorrect because it wrongly assumes that "octopus" is

Anatomy and physiology.

Size.

The giant Pacific octopus "(Enteroctopus dofleini)" is often cited as the largest known octopus species. Adults usually weigh around 15 kg (33 lb), with an arm span of up to 4.3 m (14 ft). The largest specimen of this species to be scientifically documented was an animal with a live

External characteristics.

The octopus is bilaterally symmetrical along its dorso-ventral axis; the head and foot are at one end of an elongated body and function as the anterior (front) of the animal. The head includes the mouth and brain. The foot has evolved into a set of flexible, prehensile appendages, known as "arms", that surround the mouth and are attached to each other near their base by a webbed structure. The arms can be described based on side and sequence position (such as L1, R1, L2, R2) and divided

Circulatory system.

Octopuses have a closed circulatory system, in which the blood remains inside blood vessels. Octopuses have three hearts; a systemic heart that circulates blood around the body and two branchial hearts that pump it through each of the two gills. The systemic heart is inactive when the animal is swimming and thus it tires quickly and prefers to crawl. Octopus blood contains the copper-rich protein haemocyanin to transport oxygen. This makes the blood very viscous and it requires considerable pressure to pump it around the body; octopuses' blood

Respiration.

Respiration involves drawing water into the mantle cavity through an aperture, passing it through the gills, and expelling it through the siphon. The ingress of water is achieved by contraction of radial muscles in the mantle wall, and flapper valves shut when strong circular muscles force the water out through the siphon. Extensive connective tissue lattices support the respiratory muscles and allow them to expand the respiratory chamber. The

Digestion and excretion.

The digestive system of the octopus begins with the buccal mass which consists of the mouth with its chitinous beak, the pharynx, radula and salivary glands. The radula is a spiked, muscular tongue-like organ with multiple rows of tiny teeth. Food is broken down and is forced into the oesophagus by two lateral extensions of the esophageal side walls in addition to the radula. From there it is transferred to the gastrointestinal tract, which is mostly suspended from the roof of the mantle cavity by numerous membranes. The tract consists of a crop, where the food is stored; a stomach, where food is ground down; a caecum where the

Nervous system and senses.

The octopus (along with cuttlefish) has the highest brain-to-body mass ratios of all invertebrates; it is also greater than that of many vertebrates. It has a highly complex nervous system, only part of which is localised in its brain, which is contained in a cartilaginous capsule. Two-thirds of an octopus's neurons are found in the nerve cords of its arms, which show a variety of complex reflex actions that persist even when they have no input from the brain. Unlike vertebrates, the complex motor skills of octopuses are not organised in their brain via an internal somatotopic map of its body, instead using a nonsomatotopic system unique to large-brained invertebrates.  Like other cephalopods, octopuses can distinguish the polarisation of light. Colour vision appears to vary from species to species, for example being present in "O. aegina" but absent in "O. vulgaris". Researchers believe that opsins in the skin can sense different wavelengths of light and help the creatures choose a coloration that camouflages them, in addition to light input from the eyes. Other researchers hypothesise that cephalopod eyes in species which only have a single photoreceptor protein may use chromatic aberration

Ink sac.

The ink sac of an octopus is located under the digestive gland. A gland attached to the sac produces the ink, and the sac stores it. The sac is close enough to the funnel for the octopus to

Lifecycle.

Reproduction.

Octopuses are gonochoric and have a single, posteriorly-located gonad which is associated with the coelom. The testis in males and the ovary in females bulges into the gonocoel and the gametes are released here. The gonocoel is connected by the gonoduct to the mantle cavity, which it enters at the gonopore. An optic gland creates hormones that cause the octopus to mature and age and stimulate gamete production. The gland may be triggered by environmental conditions such as temperature, light and nutrition, which thus control the timing of reproduction and lifespan.  When octopuses reproduce, the male uses a specialised arm called a hectocotylus to transfer spermatophores (packets of

Lifespan.

Octopuses have a relatively short life expectancy; some species live for as little as six months. The giant Pacific octopus, one of the two largest species of octopus, may live for as much as five years. Octopus lifespan is limited by reproduction: males can live for only a few months after mating, and females die

Distribution and habitat.

Octopuses live in every ocean, and different species have adapted to different marine habitats. As juveniles, common octopuses inhabit shallow tide pools. The Hawaiian day octopus ("Octopus cyanea") lives on coral reefs; argonauts drift in pelagic waters. "Abdopus aculeatus" mostly lives in near-shore seagrass beds. Some species are adapted to the cold,

Behaviour and ecology.

Most species are solitary when not mating, though a few are known to occur in high densities and with frequent interactions, signaling, mate defending and eviction of individuals from dens. This is likely the result of abundant food supplies combined with limited den sites. The larger Pacific striped octopus however is social, living in groups of up to 40 individuals that share dens. Octopuses hide in dens, which are typically crevices in rocky outcrops or other hard structures, though some species burrow into sand or mud. Octopuses are not territorial but generally remain in a home range; they may leave the area in search of food. They can use navigation skills to return to a den without having to retrace their outward route. They are not known to be migratory.  Octopuses bring captured prey back to the den where they can eat it safely. Sometimes the octopus catches more prey than it can eat, and the den is often surrounded by a midden of dead and uneaten food items. Other creatures, such as fish, crabs, molluscs and echinoderms, often share the den with the octopus, either because they have arrived as scavengers, or because they have survived capture.

Feeding.

Nearly all octopuses are predatory; bottom-dwelling octopuses eat mainly crustaceans, polychaete worms, and other molluscs such as whelks and clams; open-ocean octopuses eat mainly prawns, fish and other cephalopods. Major items in the diet of the giant Pacific octopus include bivalve molluscs such as the cockle "Clinocardium nuttallii", clams and scallops and crustaceans such as crabs and spider crabs. Prey that it is likely to reject include moon snails because they are too large and limpets, rock scallops, chitons and abalone, because they are too securely fixed to the rock.  A benthic (bottom-dwelling) octopus typically moves among the rocks and feels through the crevices. The creature may make a jet-propelled pounce on prey and pull it towards the mouth with its arms, the suckers restraining it. Small prey may be completely trapped by the webbed structure. Octopuses

Locomotion.

Octopuses mainly move about by relatively slow crawling with some swimming in a head-first position. Jet propulsion or backwards swimming, is their fastest means of locomotion, followed by swimming and crawling. When in no hurry, they usually crawl on either solid or soft surfaces. Several arms are extended forwards, some of the suckers adhere to the substrate and the animal hauls itself forwards with its powerful arm muscles, while other arms may push rather than pull. As progress is made, other arms move ahead to repeat these actions and the original suckers detach. During crawling, the heart rate nearly doubles, and the animal requires ten or fifteen minutes to recover from relatively minor exercise.  Most octopuses swim by expelling a jet of water from the mantle through the siphon into the sea. The physical principle behind this is that the force required to accelerate the water through the orifice produces a reaction that propels the octopus in the opposite direction. The direction of travel depends on the orientation of the siphon. When swimming, the head is at the front and the siphon is pointed backwards,

Intelligence.

Octopuses are highly intelligent; the extent of their intelligence and learning capability are not well defined. Maze and problem-solving experiments have shown evidence of a memory system that can store both short- and long-term memory. It is not known precisely what contribution learning makes to adult octopus behaviour. Young octopuses learn nothing from their parents, as adults provide no parental care beyond tending to their eggs until the young octopuses hatch.

Camouflage and colour change.

Octopuses use camouflage when hunting and to avoid predators. To do this they use specialised skin cells which change the appearance of the skin by adjusting its colour, opacity, or reflectivity. Chromatophores contain yellow, orange, red, brown, or black pigments; most species have three of these colours, while some have two or four. Other colour-changing cells are reflective iridophores and white leucophores. This colour-changing ability is also used to communicate with or warn other octopuses.  Octopuses can create

Defence.

Aside from humans, octopuses may be preyed on by fishes, seabirds, sea otters, pinnipeds, cetaceans, and other cephalopods. Octopuses typically hide or disguise themselves by camouflage and mimicry; some have conspicuous warning coloration (aposematism) or deimatic behaviour. An octopus may spend 40% of its time hidden away in its den. When the octopus is approached, it may extend an arm to investigate. 66% of "Enteroctopus dofleini" in one study had scars, with 50% having amputated arms. The blue rings of the highly venomous blue-ringed octopus are hidden in muscular skin folds which contract when the animal is threatened, exposing the iridescent warning. The Atlantic white-spotted octopus ("Callistoctopus macropus") turns bright brownish red with oval white spots all over

Pathogens and parasites.

The diseases and parasites that affect octopuses have been little studied, but cephalopods are known to be the intermediate or final hosts of various parasitic cestodes, nematodes and copepods; 150 species of protistan and metazoan parasites have been recognised. The Dicyemidae are a family of tiny worms that are found in the renal appendages of many species; it is unclear whether they are parasitic

Evolution.

The scientific name Octopoda was first coined and given as the order of octopuses in 1818 by English biologist William Elford Leach, who classified them as Octopoida the previous year. The Octopoda consists of around 300 known species and were historically divided into two suborders, the Incirrina and the Cirrina. However, more recent evidence suggests that Cirrina are merely the most basal species and are not a unique clade. The incirrate octopuses (the majority of species) lack the cirri and paired swimming fins of the cirrates. In addition, the internal shell of incirrates is either present as a pair of stylets or absent altogether.

Fossil history and phylogeny.

Cephalopods have existed for 500 million years and octopus ancestors were in the Carboniferous seas 300 million years ago. The oldest known octopus fossil is "Pohlsepia", which lived 296 million years ago. Researchers have identified impressions of eight arms, two eyes, and possibly an ink sac. Octopuses are mostly soft tissue, and so fossils are relatively rare. Octopuses, squids and cuttlefish belong to the clade Coleoidea. They are known as "soft-bodied" cephalopods, lacking the external

RNA editing.

Octopuses and other coleoid cephalopods are capable of greater RNA editing (which involves changes to the nucleic acid sequence of the primary transcript of RNA molecules) than any other organisms. Editing is concentrated in the nervous system and affects proteins involved in neural excitability and neuronal morphology. More than 60% of RNA transcripts for coleoid brains are recoded

Relationship to humans.

Cultural references.

Ancient seafaring people were aware of the octopus, as evidenced by certain artworks and designs. For example, a stone carving found in the archaeological recovery from Bronze Age Minoan Crete at Knossos (1900–1100 BC) has a depiction of a fisherman carrying an octopus. The terrifyingly powerful Gorgon of Greek mythology has been thought to have been inspired by the octopus or squid, the octopus itself representing the severed head of Medusa, the beak as the protruding tongue and fangs, and its tentacles as the snakes. The Kraken are legendary sea monsters of giant proportions said to dwell off the coasts of Norway and Greenland, usually portrayed in art as a giant octopus attacking ships. Linnaeus included it in the first edition of

Danger.

Octopuses generally avoid humans, but incidents have been verified. For example, a Pacific octopus, said to be nearly perfectly camouflaged, "lunged" at a diver and "wrangled" over his camera before it let go. Another diver recorded the encounter on video.  All species are venomous, but only blue-ringed octopuses have venom that is lethal to humans. Bites are reported each year across the animals' range from

Fisheries and cuisine.

Octopus fisheries exist around the world with total catches varying between 245,320 and 322,999 metric tons from 1986 to 1995. The world catch peaked in 2007 at 380,000 tons, and fell by a tenth by 2012. Methods to capture octopuses include pots, traps, trawls, snares, drift fishing, spearing, hooking and hand collection. Octopus

In science and technology.

In classical Greece, Aristotle (384–322 BC) commented on the colour-changing abilities of the octopus, both for camouflage and for signalling, in his "Historia animalium": "The octopus... seeks its prey by so changing its colour as to render it like the colour of the stones adjacent to it; it does so also when alarmed." Aristotle noted that the octopus had a hectocotyl arm and suggested it might be used in sexual reproduction. This claim was widely disbelieved until the 19th century. It was described in 1829 by the French zoologist Georges Cuvier, who supposed it to be a parasitic worm, naming it as a new species, "Hectocotylus octopodis". Other zoologists thought it a spermatophore; the German zoologist Heinrich Müller believed it was "designed" to detach during copulation. In 1856 the Danish zoologist Japetus Steenstrup demonstrated that it is used to transfer sperm, and only rarely detaches.  Octopuses offer many possibilities in biological research, including their ability to regenerate limbs, change the colour of

The octopus (plural octopuses) is a soft-bodied, eight-limbed mollusc of the order Octopoda (, ). Around 300 species are recognised, and the order is grouped within the class Cephalopoda with squids, cuttlefish, and nautiloids. Like other cephalopods, the octopus is bilaterally symmetric with two eyes and a beak, with its mouth at the center point of the eight limbs ("tentacle" is used as an umbrella term for cephalopod limbs; however, within a teuthological context, "arm" is used to refer to such limbs while "tentacle" is reserved for feeding appendages not found on octopuses). The soft body can rapidly alter its shape, enabling octopuses to squeeze through small gaps. They trail their eight appendages behind them as they swim. The siphon is used both for respiration and for locomotion, by expelling a jet of water. Octopuses have a complex nervous system and excellent sight, and are among the most intelligent and behaviourally diverse of all invertebrates.

八腕目(学名:)又翻译做章鱼目,通称章鱼、古称蛸,属于软体动物门头足纲。章鱼是所有头足纲、软体动物以及无脊椎动物当中最聪明的一支,章鱼完全褪去了外壳,也完全褪去了头部用于游泳的肉鳍,头部(即身体)大幅缩小、腕足大幅延长,因此却获得了头足纲动物中最灵活的行动力。许多科学家会对章鱼进行测试其智力的实验,其结果也显示章鱼学习能力和随机应变能力非常之强。章鱼目中的拟态章鱼是自然界的伪装大师,可以模拟各种海洋动物甚至植物,而章鱼属就是一般所说的章鱼,里面大部分物种均可食用,经济价值高、肉质鲜美、养殖容易,这些章鱼也是韩国、日本、中国东南沿岸地区的传统食物,对他们的饮食文化有着重要的影响力。


马克西米利安·弗朗茨 (奥地利大公)

Biography.

Maximilian Francis was born in the Hofburg Palace, Vienna. In 1780, he succeeded his uncle Prince Charles Alexander of Lorraine as "Hochmeister" (Grand Master) of the "Deutscher Orden" (Teutonic Knights).  In 1784, he became Archbishop and Elector of Cologne, living in the Electoral residence at Bonn. He remained in that office until his death in exile. In his capacity as chancellor of the Holy Roman Empire for Italy and as the Pope's deputy he crowned as Emperor in Frankfurt first his brother Leopold II in 1790, and in 1792 his nephew Francis II.  At the same time as he became Elector of Cologne, Maximilian Francis was elected to the related Bishopric of Münster and held court in Bonn, as the Archbishop-Electors of Cologne had been forced to do since the late Middle Ages. A keen patron of music, Maximilian Francis maintained a court musical establishment in which Beethoven's father was a tenor, thus playing an important role in the son's early career as a member of the same musical body of which his grandfather, also named Ludwig van Beethoven, had been "Kapellmeister".  The court organist, Christian Gottlob Neefe, was Beethoven's early mentor and teacher. Recognising his young pupil's gift both as a performer and as a composer, Neefe brought Beethoven to the court, advising Maximilian Francis to appoint him as assistant organist. Maximilian Francis, too, recognised the extraordinary abilities of the young Beethoven. In 1787, he gave Beethoven leave to visit Vienna to become a pupil of Mozart, but the visit was cut short by news of the last illness of Beethoven's mother, and evidence is lacking for any contact with Mozart.  In 1792, the Redoute was opened, making Godesberg a spa town. Beethoven played in the orchestra. After a concert given there in the presence of Joseph Haydn, another visit for studies in Vienna was planned. Beethoven went on full salary to Vienna to study with Haydn, Antonio Salieri and others. The Elector maintained an interest in the young Beethoven's progress, and several reports from Haydn to Maximilian detailing it are extant. The prince anticipated that Beethoven would return to Bonn and continue working for him, but due to the subsequent political and military situation his subject never returned, choosing to pursue a career in Vienna.  Maximilian Francis's rule over most of the Electorate ended in 1794, when his domains were overrun by the troops of Revolutionary France. During the French Revolutionary Wars, Cologne and Bonn were both occupied by the French army in the second half of 1794. As the French approached, Maximilian Francis left Bonn, as it turned out never to return, and his territories on the left bank of the Rhine eventually passed to France under the terms of the Treaty of Lunéville (1801). The Archbishop's court ceased to exist. Although Maximilian Francis still retained his territories on the right bank of the Rhine, including Münster and the Duchy of Westphalia, the Elector, grotesquely corpulent and plagued by ill health, took up residence in Vienna after the loss of his capital and remained there until his death at the age of 45, at Hetzendorf Palace in 1801. The dismantling of the court made Beethoven's relocation to Vienna permanent, and his stipend was terminated.  Beethoven planned to dedicate his First Symphony to his former patron, but the latter died before it was completed.  The Electorate of Cologne was secularised in the course of the German mediatisation of 1802–1803.

Archduke Maximilian Francis of Austria (Maximilian Franz Xaver Joseph Johann Anton de Paula Wenzel, 8 December 1756 in Vienna – 26 July 1801 in Vienna) was Elector of Cologne, and Grand Master of the Teutonic Knights. He was the youngest child of the Habsburg ruler of Austria, Maria Theresa, and her husband, Francis I, Holy Roman Emperor, for whom he was named. His siblings included emperors Joseph II and Leopold II, the Sicilian queen Maria Carolina, and the French queen Marie Antoinette. He was the last fully functioning Elector of Cologne and the second employer and patron of the young Ludwig van Beethoven.

奥地利大公马克西米利安·弗兰兹(Archduke Maximilian Francis of Austria),出生于家世显赫的贵族家庭,母亲是奥地利女大公,匈牙利女王和波希米亚女王玛丽娅·特蕾西娅,父亲是洛林公爵,神圣罗马帝国皇皇帝弗朗茨一世,同时也是神圣罗马帝国皇帝约瑟夫二世之弟。一生挚爱音乐,艺术,曾替贝多芬向莫扎特写推荐函,被普遍认为是这两位音乐才子关系的牵线者。


Biography.

Early life.

Andrey Kolmogorov was born in Tambov, about 500 kilometers south-southeast of Moscow, in 1903. His unmarried mother, Maria Y. Kolmogorova, died giving birth to him. Andrey was raised by two of his aunts in Tunoshna (near Yaroslavl) at the estate of his grandfather, a well-to-do nobleman.  Little is known about Andrey's father. He was supposedly named Nikolai Matveevich Kataev and had been an agronomist. Nikolai had been exiled from St. Petersburg to the Yaroslavl province after his participation in the revolutionary movement against the czars. He disappeared in 1919 and was presumed to have been killed in the Russian Civil War.  Andrey Kolmogorov was educated in his aunt Vera's village school, and his earliest literary efforts and mathematical papers were printed in the school journal "The Swallow of Spring". Andrey (at the age of five) was the "editor" of the mathematical section of this journal. Kolmogorov's first mathematical discovery was published in this journal: at the age of five he noticed the regularity in the sum of the series of odd numbers: formula_1 etc.  In 1910, his aunt adopted him, and they moved to Moscow, where he graduated from high school in 1920. Later that same year, Kolmogorov began to study at the Moscow State University and at the same time Mendeleev Moscow Institute of Chemistry and Technology. Kolmogorov writes about this time: "I arrived at Moscow University with a fair knowledge of mathematics. I knew in particular the beginning of set theory. I studied many questions in articles in the Encyclopedia of Brockhaus and Efron, filling out for myself what was presented too concisely in these articles."  Kolmogorov gained a reputation for his wide-ranging erudition. While an undergraduate student in college, he attended the seminars of the Russian historian S. V. Bachrushin, and he published his first research paper on the fifteenth and sixteenth centuries' landholding practices in the Novgorod Republic. During the same period (1921–22), Kolmogorov worked out and proved several results in set theory and in the theory of Fourier series.

Adulthood.

In 1922, Kolmogorov gained international recognition for constructing a Fourier series that diverges almost everywhere. Around this time, he decided to devote his life to mathematics.  In 1925, Kolmogorov graduated from the Moscow State University and began to study under the supervision of Nikolai Luzin. He formed a lifelong close friendship with Pavel Alexandrov, a fellow student of Luzin. Kolmogorov (together with Aleksandr Khinchin) became interested in probability theory. Also in 1925, he published his work in intuitionistic logic, "On the principle of the excluded middle", in which he proved that under a certain interpretation, all statements of classical formal logic can be formulated as those of intuitionistic logic. In 1929, Kolmogorov earned his Doctor of Philosophy (Ph.D.) degree, from Moscow State University.  In 1930, Kolmogorov went on his first long trip abroad, traveling to Göttingen and Munich, and then to Paris. He had various scientific contacts in Göttingen. First of all with Richard Courant and his students working on limit theorems, where diffusion processes turned out to be the limits of discrete random processes, then with Hermann Weyl in intuitionistic logic, and lastly with Edmund Landau in function theory. His pioneering work, "About the Analytical Methods of Probability Theory," was published (in German) in 1931. Also in 1931, he became a professor at the Moscow State University.  In 1933, Kolmogorov published his book, "Foundations of the Theory of Probability", laying the modern axiomatic foundations of probability theory and establishing his reputation as the world's leading expert in this field. In 1935, Kolmogorov became the first chairman of the department of probability theory at the Moscow State University. Around the same years (1936) Kolmogorov contributed to the field of ecology and generalized the Lotka–Volterra model of predator-prey systems.  In 1936, Kolmogorov and Alexandrov were involved in the political persecution of their common teacher Nikolai Luzin, in the so-called Luzin affair.  In a 1938 paper, Kolmogorov "established the basic theorems for smoothing and predicting stationary stochastic processes"—a paper that had major military applications during the Cold War. In 1939, he was elected a full member (academician) of the USSR Academy of Sciences.  During World War II Kolmogorov contributed to the Russian war effort by applying statistical theory to artillery fire, developing a scheme of stochastic distribution of barrage balloons intended to help protect Moscow from German bombers.  In his study of stochastic processes, especially Markov processes, Kolmogorov and the British mathematician Sydney Chapman independently developed the pivotal set of equations in the field, which have been given the name of the Chapman–Kolmogorov equations.  Later, Kolmogorov focused his research on turbulence, where his publications (beginning in 1941) significantly influenced the field. In classical mechanics, he is best known for the Kolmogorov–Arnold–Moser theorem, first presented in 1954 at the International Congress of Mathematicians. In 1957, working jointly with his student Vladimir Arnold, he solved a particular interpretation of Hilbert's thirteenth problem. Around this time he also began to develop, and was considered a founder of, algorithmic complexity theory – often referred to as Kolmogorov complexity theory.  Kolmogorov married Anna Dmitrievna Egorova in 1942. He pursued a vigorous teaching routine throughout his life, not only at the university level but also with younger children, as he was actively involved in developing a pedagogy for gifted children (in literature, music, and mathematics). At the Moscow State University, Kolmogorov occupied different positions, including the heads of several departments: probability, statistics, and random processes; mathematical logic. He also served as the Dean of the Moscow State University Department of Mechanics and Mathematics.  In 1971, Kolmogorov joined an oceanographic expedition aboard the research vessel "Dmitri Mendeleev". He wrote a number of articles for the "Great Soviet Encyclopedia." In his later years, he devoted much of his effort to the mathematical and philosophical relationship between probability theory in abstract and applied areas.  Kolmogorov died in Moscow in 1987, and his remains were buried in the Novodevichy cemetery.  A quotation attributed to Kolmogorov is [translated into English]: "Every mathematician believes that he is ahead of the others. The reason none state this belief in public is because they are intelligent people."  Vladimir Arnold once said: "Kolmogorov – Poincaré – Gauss – Euler – Newton, are only five lives separating us from the source of our science".

Awards and honours.

Kolmogorov received numerous awards and honours both during and after his lifetime:  The following are named in Kolmogorov's honour:

Bibliography.

A bibliography of his works appeared in Textbooks:

Andrey Nikolaevich Kolmogorov (, 25 April 1903 – 20 October 1987) was a Soviet mathematician who made significant contributions to the mathematics of probability theory, topology, intuitionistic logic, turbulence, classical mechanics, algorithmic information theory and computational complexity.

安德雷·尼古拉耶维奇·柯尔莫哥洛夫(俄语:,英语:Andrey Nikolaevich Kolmogorov,1903年-4月25日-1987年-10月20日),俄国数学家,主要研究概率论、算法信息论、拓扑学、直觉主义逻辑、紊流、经典力学和计算复杂性理论,最为人所道的是对概率论公理化所作出的贡献。他曾说:"概率论作为数学学科,可以而且应该从公理开始建设,和几何、代数的路一样"。


Biography.

Early years.

Eleanor Marx was born in London on 16 January 1855, the sixth child and fourth daughter of Karl Marx and his wife Jenny von Westphalen. She was called "Tussy" by her family from a young age. She showed an early interest in politics, even writing to political figures during her childhood. The hanging of the "Manchester Martyrs" when she was twelve, for example, horrified her and shaped her lifelong sympathy for the Fenians. Her father's story-telling also inspired an interest in literature, she could recite passages by William Shakespeare at the age of three. By her teenage years this love of Shakespeare led to the formation of the "Dogberry Club" at which she, her family and the family of Clara Collet, all recited Shakespeare whilst her father watched.  While Karl Marx was writing his major work "Das Kapital" in the family home, his youngest daughter Eleanor played in his study. Marx invented and narrated a story for Eleanor based on an antihero called Hans Röckle. Eleanor reports that this was one of her favourite childhood stories. The story is significant because it offered Eleanor lessons through allegory of Marx's critique of political economy which he was writing in "Das Kapital". As an adult, Eleanor was involved in translating and editing volumes of "Das Kapital". She also edited Marx's lectures "Value, Price and Profit" and "Wage Labour and Capital", which were based on the same material, into books. Eleanor Marx's biographer, Rachel Holmes, writes: "Tussy's childhood intimacy with [Marx] whilst he wrote the first volume of "Das Kapital" provided her with a thorough grounding in British economic, political and social history. Tussy and "Capital" grew up together".  At the age of sixteen, Eleanor became her father's secretary and accompanied him around the world to socialist conferences. A year later, she fell in love with Prosper-Olivier Lissagaray, a journalist and participant of the Paris Commune, who had fled to London after the Commune's suppression. Although he agreed with the man politically, Karl Marx disapproved of the relationship because of the age gap between the two, Lissagaray being 34 years old. In May 1873 Eleanor moved away from home to Brighton working as a schoolteacher; she lived at 6 Vernon Terrace in the Montpelier suburb, returning to London in September 1873.  In 1876 she helped Lissagaray write "History of the Commune of 1871", and later translated it into English. Her father liked the book but was still disapproving of his daughter's relationship with its author. By 1880 Karl changed his view of the situation, allowing her to marry him. However, by then Eleanor herself was having second thoughts. She terminated the relationship in 1882.  In the early 1880s, she had to nurse her ageing parents, but her mother died in December 1881. From August 1882 she also cared for her young nephew Jean Longuet for several months, easing the burden on her elder sister, Jenny Longuet, who died in January 1883 of bladder cancer. Her father died two months later, in March 1883. After this, Eleanor and Edward Aveling, overseen by Friedrich Engels, prepared the first English language edition of "Das Kapital" volume I, published in 1887. On Engels death in 1895, they together sorted and stored her father's extensive papers.

Career.

In 1884, Eleanor joined the Social Democratic Federation (SDF) led by Henry Hyndman and was elected to its executive. During her work in the SDF, she met Edward Aveling, with whom she would spend the rest of her life despite his faithlessness, thievery from the movement, and mental cruelty.

Socialist League.

In 1885, after some bitter polemics, there was a split in the organization. Eleanor Marx and some others left SDF, and founded the rival Socialist League.  The split had two root causes: personality problems, as Hyndman was accused of leading the SDF in a dictatorial fashion, and disagreements on the issue of internationalism. In this point Hyndman was accused by Marx among others of nationalist tendencies. He was, for example, opposed to Marx's idea of sending delegates to the French Workers' Party calling the proposal a "family manoeuvre", since Eleanor Marx's sister Laura and her husband Paul Lafargue were members of that party. Therefore, both Marx and Aveling became founding members of the Socialist League, whose most prominent member was William Morris.  Other leaders of the Socialist League were Ernest Belfort Bax, Sam Mainwaring, and Tom Mann, the latter two being representatives of the working class. Annie Besant was also an active member.  Marx wrote a regular column called "Record of the Revolutionary International Movement" for the Socialist League's monthly newspaper, "Commonweal."  In 1884, Marx met Clementina Black, a painter and trade unionist, and became involved in the Women's Trade Union League. She would go on to support numerous strikes including the Bryant & May strike of 1888 and the London Dock Strike of 1889. She spoke to the Silvertown strikers at an open meeting in November 1889 alongside her friends Edith Ellis and Honor Brooke. She helped organise the Gasworkers' Union and wrote numerous books and articles.  In 1885, she helped organise the International Socialist Congress in Paris. The following year, she toured the United States along with Aveling and the German socialist Wilhelm Liebknecht, raising money for the Social Democratic Party of Germany.  By the late 1880s, the Socialist League was deeply divided between those advocating political action and its opponents – who were themselves split between those like William Morris who felt that parliamentary campaigns represented inevitable compromises and corruptions, and an anarchist wing which opposed all electoral politics as a matter of principle. Marx and Aveling, as firm advocates of the principle of participation in political campaigns, found themselves in an uncomfortable minority in the party. At the 4th Annual Conference of the Socialist League the Bloomsbury branch, to which Marx and Aveling belonged, moved that a meeting of all socialist bodies should be called to discuss the formation of a united organisation. This resolution was voted down by a substantial margin, as was another put forward by the same branch in support of contesting seats in both local and parliamentary elections. Moreover, the Socialist League at this occasion suspended the 80 members of the Bloomsbury branch on the grounds that the group had put up candidates jointly with the SDF, against the policy of the party. The Bloomsbury branch thus exited the Socialist League for a new, albeit brief, independent existence as the Bloomsbury Socialist Society.

Bloody Sunday (London).

Along with many other leading Socialists, Eleanor took active role in organizing the London demonstration of 13 November 1887 that resulted in the suppression of the Bloody Sunday (1887). Several other demonstrations followed in the aftermath, with Eleanor urging the radical line.In the aftermath of Bloody Sunday, Marx wrote a report on the brutal treatment of women activists and protestors at the hands of police, decrying their actions of targeting women.  In 1893, Keir Hardie founded the Independent Labour Party (ILP). Marx attended the founding conference as an observer, while Aveling was a delegate. Their goal of shifting the ILP's positions towards Marxism failed, however, as the party remained under a strong Christian socialist influence. In 1897, Marx and Aveling re-joined the Social Democratic Federation, like most former members of the Socialist League.

Translation Work.

After acquiring admission into the Reading Room of the British Museum, Eleanor first began work as a paid translator during the late 1870s. She spent many days here, taking information and working on her translations.In the late 1880s, Eleanor accomplished the first English translation of "Madame Bovary". Additionally, Eleanor translated "Reuben Sachs" by Amy Levy to German. Eleanor was involved as a translator or editor in 14 known works.

Involvement in theatre.

In the 1880s, Eleanor Marx became more interested in theatre and took up acting, believing in its potential for promulgating socialism. In 1886, she performed a ground breaking if critically unsuccessful reading of Henrik Ibsen's "A Doll's House" in London, with herself as Nora Helmer, Aveling as Torvald Helmer, and George Bernard Shaw as Krogstad.  She also translated various literary works, including the first English translation of Gustave Flaubert's "Madame Bovary". She expressly learnt Norwegian in order to translate Ibsen's plays into English, and in 1888, was the first to translate "An Enemy of Society". Two years later, the play was revised and renamed "An Enemy of the People" by William Archer. Marx also translated Ibsen's "The Lady from the Sea" in 1890.

Death and legacy.

In 1898, Eleanor discovered that the ailing Edward Aveling had secretly married a young actress, to whom he remained committed. Aveling's illness seemed to her to be terminal, and Eleanor was deeply depressed by the faithlessness of the man she loved.  On 31 March 1898, Eleanor sent her maid to the local chemist with a note to which she signed the initials of the man the chemist knew as "Dr. Aveling," asking for chloroform (some sources say "padiorium") and a small quantity of hydrogen cyanide (then called "prussic acid") for her dog. On receiving the package, Eleanor signed a receipt for the poisons, sending the maid back to the chemists to return the receipt book. Eleanor then retired to her room, wrote two brief suicide notes, undressed, got into bed, and swallowed the poison.  The maid discovered Eleanor in bed, scarcely breathing, when she returned. A doctor was called for but Eleanor had died by the time he arrived. She was 43. A "post mortem" examination determined the cause of death to have been poison. A subsequent coroner's inquest delivered a verdict of "suicide while in a state of temporary insanity," clearing Aveling of criminal wrongdoing, but he was widely reviled throughout the socialist community as having caused Eleanor to take her life.  A funeral service was held in a room at the London Necropolis railway station at Waterloo on 5 April 1898, attended by a large throng of mourners. Speeches were made by Aveling, Robert Banner, Eduard Bernstein, Pete Curran, Henry Hyndman and Will Thorne. Following the memorial, Eleanor Marx's body was taken by rail to Woking and cremated. An urn containing her ashes was subsequently kept safe by a succession of left wing organisations, including the Social Democratic Federation, the British Socialist Party, and the Communist Party of Great Britain, before finally being buried alongside the remains of Karl Marx and other family members in the tomb of Karl Marx at Highgate Cemetery in London in 1956.  On 9 September 2008 an English Heritage blue plaque was placed on the house at 7 Jews Walk, Sydenham, south-east London, where Eleanor spent the last few years of her life.

Jenny Julia Eleanor Marx (16 January 1855 – 31 March 1898), sometimes called Eleanor Aveling and known to her family as Tussy, was the English-born youngest daughter of Karl Marx. She was herself a socialist activist who sometimes worked as a literary translator. In March 1898, after discovering that Edward Aveling, her partner and a prominent British Marxist, had secretly married a young actress in June of the previous year, she poisoned herself at the age of 43.

爱琳娜·马克思或译艾琳娜·马克思(英语:Eleanor Marx Aveling,1855年-1月16日-1898年-3月31日,生于英国伦敦,卒于英国伦敦),是德国社会学家卡尔·马克思与妻子燕妮·马克思所生的小女儿。她曾任马克思的秘书,是一位社会活动家和翻译家。1898年3月,她发现丈夫爱得华·艾威林与情妇已于上一年6月秘密结婚,故服毒自杀,终年43岁。


Taxonomy.

The green sea turtle is a member of the tribe Chelonini. A 1993 study clarified the status of genus "Chelonia" with respect to the other marine turtles. The carnivorous "Eretmochelys" (hawksbill), "Caretta" (loggerhead) and "Lepidochelys" (Ridley) were assigned to the tribe Carettini. Herbivorous "Chelonia" warranted their status as a genus, while "Natator" (flatback) was further removed from the other genera than previously believed.  The species was originally described by Linnaeus in 1758 as "Testudo mydas". In 1868, Marie Firmin Bocourt named a particular species of sea turtle "Chelonia agassizii". This "species" was referred to as the "black sea turtle". Later research determined Bocourt's "black sea

Description.

Its appearance is that of a typical sea turtle. "C. mydas" has a dorsoventrally flattened body, a beaked head at the end of a short neck, and paddle-like arms well-adapted for swimming. Adult green turtles grow to long. The average weight of mature individuals is and the average carapace length is. Exceptional specimens can weigh or even more, with the largest known "C. mydas" having weighed and measured in carapace length.  Anatomically, a few characteristics distinguish the green turtle from the other members of its family. Unlike its close relative the hawksbill turtle, the green turtle's snout is very short and its beak is unhooked. The neck cannot be pulled into the shell. The sheath of the

Distribution.

The range of the green sea turtle extends throughout tropical and subtropical oceans worldwide. The two major subpopulations are the Atlantic and the eastern Pacific subpopulations. Each population is genetically distinct, with its own set of nesting and feeding grounds within the population's known range. One of the genetic differences between the two subpopulations is the type of mitochondrial DNA found in individual's cells. Individuals from rookeries in the Atlantic Ocean and Mediterranean Sea have a similar type of mitochondrial DNA, and individuals from the Pacific and Indian Oceans have another type of Mitochondrial DNA. Their native range includes tropical to subtropical waters along continental coasts and islands between 30°N and 30°S. Since green sea turtles are a migrating species, their global distribution spans into the open ocean. The differences in mitochondrial DNA more than likely stems from the populations being isolated from each other by the southern tips of both South America and Africa with no warm waters for the green sea turtles to migrate through. The green sea turtle is estimated to inhabit coastal areas of more than 140 countries, with nesting sites in over 80 countries worldwide throughout the year. In the United States Atlantic coast, green sea turtles can be found from Texas and north to Massachusetts. In the United States Pacific coast, they have been found from southern California north to the southernmost tip of Alaska. The largest populations of green sea turtles within the United States coastline are in the Hawaiian Islands and Florida. Globally, the largest populations of sea turtles are in the Great Barrier Reef in Australia and the Caribbean islands.

Atlantic subpopulation.

The green sea turtle can generally be found throughout the Atlantic Ocean. Although the species is most abundant in tropical climates, individuals have been spotted as far north as Canada in the western Atlantic, and the British Isles in the east. The subpopulation's southern range is known until past the southern tip of Africa in the east and Argentina in the western Atlantic. The major nesting sites can be found on various islands in the Caribbean, along the eastern shores of the continental United States, the eastern coast of the South American continent and most notably, on isolated North Atlantic islands.  In the Caribbean, major nesting sites have been identified on Aves Island,

Indo-Pacific subpopulation.

In the Pacific, its range reaches as far north as the southern coast of Alaska and as far south as Chile in the east. The turtle's distribution in the western Pacific reaches north to Japan and southern parts of Russia's Pacific coast, and as far south as the northern tip of New Zealand and a few islands south of Tasmania. The turtles can be found throughout the Indian Ocean.  Significant nesting grounds are scattered throughout the entire Pacific region, including Mexico, the Hawaiian Islands, the South Pacific, the northern coast of Australia, and Southeast Asia. Major Indian Ocean nesting colonies include India, Pakistan, and other coastal countries. The east coast of the African continent hosts a few nesting grounds, including

Habitat.

Green sea turtles move across three habitat types, depending on their life stage. They lay eggs on beaches. Mature turtles spend most of their time in shallow, coastal waters with lush seagrass beds. Adults frequent inshore bays, lagoons, and shoals with lush seagrass meadows. Entire generations often migrate between one pair of feeding and nesting areas. Green sea turtles, "Chelonia mydas", are classified as an aquatic species and are distributed around the globe in warm tropical to subtropical waters. The environmental parameter that limits the distribution of the turtles is ocean

Ecology and behavior.

As one of the first sea turtle species studied, much of what is known of sea turtle ecology comes from studies of green turtles. The ecology of "C. mydas" changes drastically with each stage of its life history. Newly emerged hatchlings are carnivorous, pelagic organisms, part of the open ocean mininekton. In contrast, immature juveniles and adults are commonly found in seagrass meadows closer inshore as herbivorous grazers.

Diet.

The diet of green turtles changes with age. Juveniles are carnivorous, but as they mature they become omnivorous. Young sea turtles eat fish eggs, molluscs, jellyfish, small invertebrates, worms, sponges, algae, and crustaceans. Green sea turtles

Predators and parasites.

Only human beings and the larger sharks feed on "C. mydas" adults. Specifically, tiger sharks ("Galeocerdo cuvier") hunt adults in Hawaiian waters. Juveniles and new hatchlings have significantly more predators, including crabs, small marine mammals and shorebirds. Additionally, their eggs are vulnerable to predation by scavengers like red foxes and golden jackals.  Green sea turtles have a variety of parasites including barnacles, leeches, protozoans,

Life cycle.

Green sea turtles migrate long distances between feeding sites and nesting sites; some swim more than to reach their spawning grounds. Beaches in Southeast Asia, India, islands in the western Pacific, and Central America are where Green sea turtles breed. Mature turtles often return to the exact beach from which they hatched. Females usually mate every two to four years. Males, on the other hand, visit the breeding areas every year, attempting to mate. Mating seasons vary between populations. For most "C. mydas" in the Caribbean, mating season is from June to September. The French Guiana nesting subpopulation nests from March

Breathing and sleep.

Sea turtles spend almost all their lives submerged, but must breathe air for the oxygen needed to meet the demands of vigorous activity. With a single explosive exhalation and rapid inhalation, sea turtles can quickly replace the air in their lungs. The lungs permit a rapid exchange of oxygen and prevent gases from being trapped during deep dives. Sea turtle blood can deliver oxygen efficiently to body tissues even at the pressures encountered during diving. During routine

Physiology and sensory modalities.

Green sea turtles tend to have good vision, well adapted to a life at sea. The turtles can see many colors, but are most sensitive to light from violet to yellow or wavelengths of 400 to 600 nanometers. They do not see many colors in the orange to red portion of the light spectrum. On land, however, the sea turtles are nearsighted because the lenses in the eyes are spherical and adjusted to refraction underwater. Sea turtles have no external ear and only one ear bone, called the columella. With one ear bone, the turtles can only hear low frequency sounds, from 200 to 700 Hz. Sounds can also be detected through vibrations of the head, backbone, and shell. The nose of the turtle has two external openings and connects to the roof of the mouth through internal openings. The lower surface of the nasal passage has two sets of sensory cells called the Jacobson's organ. The turtle can use this organ to smell by pumping water in and out of its nose.  Since green sea turtles migrate long distances during breeding seasons, they have special adaptive systems in order to navigate. In the open ocean, the turtles navigate using wave directions, sun light, and temperatures. The sea turtles also contain an internal magnetic compass.

Unique characteristics and features.

The green sea turtles exhibit sex differences by their development and appearance. As adult turtles, males are easily distinguishable from the females by having a longer tail (visibly extending past the shell) and longer claws on the front flippers. The hatching time and sex of the turtles are determined by the incubation temperature of the nest. Hatchings occur more quickly in nests that are warmer than nests that are in cooler conditions. Warm nesting sites above 30 degrees Celsius favor the development of females, whereas nesting sites below 30 degrees Celsius produce males. The position of the egg in the nest also affects sex-determination. Eggs in the center tend to hatch as females due to the warmer

Importance to humans.

Historically, the turtles' skin was tanned and used to make handbags, especially in Hawaii. Ancient Chinese considered the flesh of sea turtles a culinary delicacy, including and especially "C. mydas". Particularly for this species, the turtle's fat, cartilage, and flesh, known as calipee, are sought as ingredients for making turtle soup, a popular 19th-century American dish.  In Java, Indonesia, sea turtle eggs were a popular delicacy. However, the turtle's flesh is regarded as "ḥarām" or "unclean" under Islamic law (Islam is Java's primary religion). In Bali, turtle meat was a prominent feature at ceremonial and religious feasts. Turtles were harvested in the remotest parts of the Indonesian archipelago. Bali has been importing sea turtles since the 1950s, as its own turtle supplies became depleted. The mostly Hindu Balinese do not eat the eggs, but sell them instead to local Muslims.  Commercial farms, such as the Cayman Turtle Farm in the West Indies, once bred them for commercial sale of turtle meat, turtle oil (rendered from the fat), turtle shell, and turtle leather made from the skin. The farm's initial stock was in large part from "doomed" eggs removed from nests threatened by erosion, flooding, or in chemically hostile soil. The farms held as many as 100,000 turtles at any one time. When the international markets were closed by regulations that did not

Conservation.

In recent decades, sea turtles have moved from unrestricted exploitation to global protection, with individual countries providing additional protection, although serious threats remain unabated. All populations are considered "Threatened".

Threats.

Human action presents both intentional and unintentional threats to the species' survival. Intentional threats include continued hunting, poaching and egg harvesting. More dangerous are unintentional threats, including boat strikes, fishermen's nets that lack turtle excluder devices, pollution and habitat destruction. Chemical pollution may create tumors; effluent from harbors near nesting sites may create disturbances; and light pollution may disorient hatchlings. Habitat loss usually occurs due to human development of nesting areas. Beach-front construction, land "reclamation" and increased tourism are examples of such development. An infectious tumor-causing disease, fibropapillomatosis, is also a problem in some populations. The disease kills a sizeable fraction of those it infects, though some individuals seem to resist the disease. In addition, at least in the Southwestern Atlantic (Río de la Plata, Uruguay), exotic invasive species such as the rapa whelk Rapana venosa, were reported massively bio-fouling immature green turtles, reducing buoyancy, increasing drag, and causing severe injuries to the carapace. Because of

Global initiatives.

The International Union for the Conservation of Nature (IUCN) has repeatedly listed green sea turtles in its Red List under differing criteria. In 1982, they officially classified it as an endangered species. The 1986, 1988, 1990, 1994, and the landmark 1996 edition of the IUCN Red List, retained the listing.  In 2001, Nicholas Mrosovsky filed a delisting petition, claiming some green turtle populations were large, stable and in some cases, increasing. At the time, the species was listed under the strict EN A1abd criteria. The IUCN Standards and Petitions Subcommittee ruled that visual counts of nesting females could not be considered "direct observation" and thus downgraded the species' status to EN A1bd—retaining the turtle's endangered status.  In 2004, the IUCN reclassified "C. mydas" as endangered under the EN A2bd criteria, which essentially states the wild populations face a high risk of extinction because of several factors. These factors include a probable population reduction of more than 50% over the past

Country-specific initiatives.

In addition to management by global entities such as the IUCN and CITES, specific countries around the world have undertaken conservation efforts.  The Indonesian island of Bali has traditional uses that were considered sustainable, but have been questioned considering greater demand from the larger and wealthier human population. The harvest was the most intensive in the world. In 1999, Indonesia restricted turtle trade and consumption because of the decreasing population and threat of a tourist boycott. It rejected a request made by Bali Governor I Made Mangku Pastika in November 2009 to set a quota of 1,000 turtles to be killed in Hindu religious ceremonies. While conservationists respect the need for turtles in rituals, they wanted a smaller quota.  Ecotourism is one initiative in Sabah, Malaysia. The island of

Genetics.

The genome of "Chelonia mydas" was sequenced in 2013 to examine the development and evolution of the turtle body plan.

The green sea turtle ("Chelonia mydas"), also known as the green turtle, black (sea) turtle or Pacific green turtle, is a species of large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans, but it is also found in the Indian Ocean. The common name refers to the usually green fat found beneath its carapace, not to the color of its carapace, which is olive to black.

绿蠵龟(学名:'、英文:英语:green sea turtle),又称青海龟,是海洋中的爬行类动物,是海龟属下的唯一一种。一生中大多的时间都在海中生活,但演化过程中仍然保留了部分祖先的生活方式,所以必须回到出生地上产卵,繁育后代,形成了一种较独特的生活习性。