Geography.

Niihau is located about west of Kauai, and the tiny, uninhabited island of Lehua lies north of Niihau. Niihau's dimensions are 6.2 miles by 18.6 miles (10 km × 30 km). The maximum elevation (Paniau) is. The island is about 6 million years old, making it geologically older than the 5.8-million-year-old neighboring island of Kauai to the northeast. Niihau is the remnant of the southwestern slope of what was once a much larger volcano. The entire summit and other slopes collapsed into the ocean in a giant prehistoric landslide.

Climate.

The island is relatively arid because it lies in the rain shadow of Kauai, and lacks the elevation needed to catch significant amounts of trade wind rainfall. Niihau, therefore, depends on winter Kona storms for its rain, when more northerly weather systems intrude into the region. As such, the island is subject to long periods of drought. Historical droughts on Niihau have been recorded several times, one in 1792 by Captain James Cook's former junior officer, George Vancouver, who had been told that the people of Niihau had abandoned the island because of a severe drought and had moved to Kauai to escape famine.

Flora and fauna.

As an arid island, Niihau was barren of trees for centuries – Captain James Cook reported it treeless in 1778. Aubrey Robinson, grandfather of current owners Bruce Robinson and Keith Robinson, planted 10,000 trees per year during much of his ownership of the island; Robinson's afforestation efforts increased rainfall in the dry climate. Island co-owner Keith Robinson, a noted conservationist, preserved and documented many of Niihau's natural plant resources. The island is designated as a critical habitat for the "ōlulu", an endemic and endangered species of Hawaiian lobelioid. "Aylmer robinsonii", a Pritchardia palm tree named for Keith Robinson's uncle Aylmer Robinson, is an endangered species native to Niihau.  Several bird species thrive on Niʻihau. The largest lakes on the island are Hālaliʻi Lake, Halulu Lake and Nonopapa Lake. These intermittent playa lakes on the island provide wetland habitats for the "ʻalae keʻokeʻo" (Hawaiian coot), the "āeʻo" (black-winged stilt), and the "koloa maoli" (Hawaiian duck). The critically endangered Hawaiian monk seal ("Monachus schauinslandi") is found in high numbers on Niʻihau's shores. Robinson states that Niʻihau's secluded shoreline offers them a safe haven from habitat encroachments. According to Robinson, conditions there are better than the government refuges of the Northwestern Hawaiian Islands. When the Robinsons originally purchased Niʻihau, no monk seals were present, because they lived in the northwestern part of the Hawaiian island chain, Necker and Midway islands. They have been relocated to the main Hawaiian island chain by NOAA fisheries over the past thirty years, and some have found homes on Niʻihau.  Big game herds, imported from stock on Molokai Ranch in recent years, roam Niihau's forests and flatlands. Eland and aoudad are abundant, along with oryxes, wild boars and feral sheep. These big game herds provide income from hunting safari tourism.

History.

Prior to the unification of the Kingdom of Hawaii under Kamehameha I, Niihau was ruled by the. Kahelelani was the first of the Niihau alii. His name is now used to refer to the "Niihau kahelelani", the puka shell of the wart turbans ("Leptothyra verruca"), used to make exquisite Niihau shell jewelry. Kāʻeokūlani was a ruler of northern Niihau who unified the island after defeating his rival, a chief named Kawaihoa. A stone wall () across a quarter of the island's southern end marked the boundaries of the two chiefs: Kāeo's land was identified by black stones and Kawaihoa's by white stones. Eventually, a great battle took place, known as Pali Kamakaui. Kāeo's two brothers from the island of Maui, Kaiana and his half-brother Kahekili II, the King of Maui, fought for Kāeo, and Niihau was united under his rule. Kawaihoa was banished to the south end of the island and Kāeo moved to the middle of the island to govern. Kāeo married the Queen Kamakahelei, and a future king of Niihau and Kauai named Kaumualii was born in 1790. Kauai and Niihau are said to have carried the "highest blood lines" in the Hawaiian Islands.  Kamehameha managed to unify all of the islands by 1795, except for Kauai and Niihau: Two attempts to conquer those islands had failed, and Kamehameha lost many men: bodies covered the beaches on Kauai's eastern shores. Finally, in 1810, Kamehameha amassed a great fleet, and Kaumualii, the last independent, surrendered rather than risk further bloodshed. Independence again became feasible after Kamehameha's death in 1819, but was put down when Kamehameha's widow Kaʻahumanu kidnapped Kaumualii and forced him to marry her. Thereafter Niihau remained part of the unified Kingdom of Hawaii. Elizabeth McHutchison Sinclair (1800–1892) purchased Niihau and parts of Kauai from Kamehameha V in 1864 for $10,000 in gold. Sinclair chose Niihau over other options, including Waikīkī and Pearl Harbor. By around 1875, Niihau's population consisted of about 350 Native Hawaiians, with 20,000 sheep. This era marked the end of the art of Hawaiian mat-weaving made famous by the people of Niihau. ("Cyperus laevigatus"), a native sedge, used to grow on the edges of Niihau's three intermittent lakes. The stems were harvested and used to weave (mats), considered the "finest sleeping mats in Polynesia". The mats were valued by and foreign visitors alike, but by the end of the 19th century, Hawaiians had stopped weaving due to changes in population, culture, economics, and the environment.  In 1915, Sinclair's grandson Aubrey Robinson closed the island to most visitors. Even relatives of the inhabitants could visit only by special permission. Upon Aubrey's death in 1939 the island passed to his son Aylmer, and in 1968 to Aylmer's youngest brother Lester. Upon Lester's wife Helen's death, the island passed to his sons Bruce Robinson and Keith Robinson, the current co-owners. (See Sinclair-Robinson family tree)  Niihau played a small role during the attack on Pearl Harbor on December 7, 1941. In what has come to be called the Niihau Incident (or the Battle of Niihau), a Japanese pilot whose Zero had been hit crash-landed on the island hoping to rendezvous with a rescue submarine. The pilot was apprehended and later escaped with the assistance of local Japanese residents, but he was killed shortly afterwards.  Despite its self-imposed isolation, Niihau has a long-standing relationship with the U.S. military dating from 1924. There is a small Navy installation on the island. No military personnel are permanently stationed there, but the U.S. military has used the island for training special operations units, which included hiring Hawaiians who live on Niihau as "enemy" trackers.

Society.

Politics.

The island of Niihau was considered as a possible location for the United Nations headquarters in 1944 by Franklin D. Roosevelt, who had visited Hawaii in 1934. Under Cordell Hull, Roosevelt's Secretary of State, the State Department seriously studied the proposal.  In 2004 President George W. Bush received all but one of the 40 votes cast on the island. The remaining vote was cast for Green Party nominee David Cobb. 51 registered voters did not cast ballots. In 2006 Dan Akaka received 60% of votes in the 2006 Senate election to Cynthia Thielen's 36%. In 2008, Niihau's precinct was one of only 3 of Hawaii's 538 precincts to vote for John McCain over Barack Obama. McCain received 35 votes, Obama received 4, and Cynthia McKinney received 1. In the 2016 presidential election, nearly 60% of the vote went for Donald Trump.

Population.

The 2010 census states that there were 170 people living on the island. However, witness accounts estimate that the population actually ranges between 35–50 people. Some support themselves largely by subsistence fishing and farming, while others depend on welfare. All residents live rent-free, and meat is free. Niihau has no telephone services and no paved roads. Horses are the main form of transportation; bicycles are also used. There are no power lines; solar power provides all electricity. There is no plumbing or running water on the island. Water comes from rainwater catchment. The Robinson family established most of these conditions. There is no hotel, and barges deliver groceries from Kauai, often purchased by relatives, with free shipping.  Residents generally speak the Niihau dialect of Hawaiian as their first language, in part encouraged by terms in the original purchase contract which obligated the new owners to help preserve Hawaiian culture and tradition. The Niihau dialect differs from modern standard Hawaiian in that, for example, and are the most common realizations of the phonemes and, respectively. Niihau is the only island where Hawaiian is spoken as a primary language. Oral tradition maintains that the Niihau dialect is closer to the Hawaiian register spoken during the time of contact with Europeans; there is linguistic evidence to support this claim, such as the pronunciation of k as /t/. English is the second language.  Some residents have radio and television sets, although limited reception effectively limits the latter to watching pre-recorded media. Niihau is subject to regular droughts that occasionally force the population to evacuate to Kauai temporarily, until rainfall replenishes their water supply. Residents commonly also commute to Kauai for work, medical care, or school, and many of them call both islands home. To avoid a long boat ride, the island's owners maintain an Agusta A109 helicopter for emergencies and for transporting Navy contractors and residents to and from Kauai. Helicopter tours and safaris help offset the costs of this service.  A form of ipu art is known to have developed solely on the island of Niihau. In this method, after a design is carved in the skin of a fresh gourd, it is filled with dye which, after several weeks, changes the color of the uncarved portions of the surface where the skin is intact. Hawaiian music plays a central role on the island, with a cappella singers making use of only two or three tones and changing rhythms. Ukulele and guitar playing is nearly ubiquitous among the islanders, and there are three separate styles of slack-key music, with an older style originating from Kohala.

Education.

The Hawaii Department of Education operates the Niihau School, a K-12 school. Academic subjects and computer literacy are combined with teaching students to "thrive from the land". The school is powered entirely by solar power. The number of students varies from 25 to 50 since families often travel between Niihau and Kauai. Schoolchildren may stay with relatives in west Kauai, where they attend one of two Niihau-focused public charter schools. At the Ke Kula Niihau o Kekaha school, students speak primarily the Niihau dialect through the early elementary grades, and then Hawaiian and English through grade 12. The school has a digital recording and video system, which helps to preserve and teach traditional Niihau and Hawaiian culture. At the other west Kauai school, Kula Aupuni Niihau a Kahelelani Aloha (KANAKA), English is used in all grades, while still supporting the Niihau dialect. Both schools foster the culture, values, and spirituality of Niihau.

Economy.

Approximately 80% of Niihau's income comes from a small Navy installation atop 1,300-foot-high cliffs. Remote-controlled tracking devices are used for testing and training with Kaua'i's Pacific Missile Range Facility. Modern missile defense tests are conducted at the site for the U.S. and its allies. The installation brings in millions of dollars a year, and provides the island with a stable economic base without the complexity of tourism or industrial development.  The sale of shells and shell jewelry is an additional source of income. Its beaches are known for their "pūpū", tiny shells that wash onto shore during winter months. Species used for shell leis includes "momi" ("Euplica varians"), "laiki" or rice shells ("Mitrella margarita") and "kahelelani" ("Leptothyra verruca"). The shells and jewelry are so popular that Governor Linda Lingle signed a bill in 2004 to protect "lei pūpū o Niihau" (Niihau shell leis) from counterfeiting. A single, intricate Niihau shell lei can sell for thousands of dollars.  Many residents of Niihau were once employees of Niihau Ranch, farming cattle and sheep until the Robinsons shut down the operation in 1999. It had not been profitable for most of the 20th century. Honey cultivation was also no longer viable by 1999. Kiawe charcoal was once a large-scale export, but aggressive Mexican price competition ended that as well. Mullet farming has been popular on Niihau, with ponds and lakes stocked with baby mullet, which reach apiece before being harvested and sold on Kauai and Oahu.  Bruce Robinson, Niihau's co-owner, is seeking and considering new forms of non-invasive income generation. Depending on feasibility, impact, and ecological footprint on the ecosystem and culture, possibilities include: JP-8 generation by the lignocellulose process; military, including a possible runway; and windmill energy production. Robinson has declined offers to purchase sand from Niihau's beaches, because of adverse environmental effects.

Tourism.

Niihau's owners have offered half-day helicopter and beach tours of the island since 1987, although contact with residents is avoided and no accommodation exists. Since 1992, hunting safaris provide income via tourists who pay to visit the island to hunt eland, aoudad, and oryx, as well as wild sheep and boars. Any meat the hunters do not take with them is given to the village.

Niihau (Hawaiian: ) anglicized as Niihau ( ) is the westernmost main and seventh largest inhabited island in Hawaii. It is southwest of Kauai across the Kaulakahi Channel. Its area is. Several intermittent playa lakes provide wetland habitats for the Hawaiian coot, the Hawaiian stilt, and the Hawaiian duck. The island is designated as critical habitat for "Brighamia insignis", an endemic and endangered species of Hawaiian lobelioid. The United States Census Bureau defines Niihau and the neighboring island and State Seabird Sanctuary of Lehua as Census Tract 410 of Kauai County, Hawaii. Its 2000 census population was 160; Its 2010 census population was 170.

Niihau (zvaný také jako Forbidden Isle – Zakázaný ostrov) je nejmenší obydlený ostrov z osmi hlavních Havajských ostrovů, které se nacházejí v severovýchodní části Tichého oceánu. Žije zde asi 170 obyvatel (odhad z roku 2010) a ostrov má rozlohu 181,04 km2. Niihau je částí státu Havaj, který je 50. spolkovým státem Spojených států amerických.


Geography and location.

Zaporizhia (direct translation is "beyond the rapids") takes its name from a geographic area downstream of the Dnieper river pass the ninth rapid (see Dnieper Rapids). In the 1930s when the Dnieper Hydroelectric Station was built, these rapids were flooded. Only granite cliffs, rising to the height of, testify to the original rocky terrain of the region.

History.

Khortytsia has been continuously inhabited during the last five millennia. Other islands in the immediate vicinity also contain indications of intensive occupation during the Proto-Indo-European and Scythian periods. The island of Small Khortytsia is known for its Scythian remains and a derelict Cossack fortress. The islet of Sredeny Stih (to the northeast of Khortytsia), excavated during construction of the hydroelectric station in 1927, gave its name to the Sredny Stog culture.  In the Early Middle Ages, Khortytsia was a key centre for the trade route from the Varangians to the Greeks. In his treatise "De Administrando Imperio", Emperor Constantine VII mentions the island of "St. George" immediately downstream from the rapids. He reports that, while passing through the rapids, the Rus would be easy prey for the nomadic Pechenegs. Indeed, the Kiev Rus' prince Svyatoslav I was attacked and killed during his attempt to cross the rapids in 972. The earliest record about a stronghold known as a "sich" refers to the one was located on the island of Small Khortytsia (Mala Khortytsia Island) and was established by the Volhynian prince Dmytro Vyshnevetsky. The Small Khortytsia Island is 20 times smaller than Khortytsia itself. The first Khortytsia Sich existed six years (1552–1558). There are few others locations downstream past the rapids (Zaporizhia area) where the Zaporizhian Sich was located. There are eight of them: Bazavluk (1593–1630), Mykytyn (1628–1652), Chortomlyk (1652–1709), Kamin (1709–1711), Oleshkiv (1711–1734), Pidpilna (1734–1775). All these places were at river crossings. The uprising led by Bohdan Khmelnytsky was started at the Mykytyn Sich in 1648. Legends state, that cossacks wrote the notorious Reply of the Zaporozhian Cossacks to Sultan Mehmed IV of the Ottoman Empire on Khortytsia. In the 1775, the Sich was destroyed by the Russian general Tekhely on the order of Catherine the Great. The Zaporozhian Cossacks as a result were displaced, many eventually settling on the Kuban river in the Caucasus area. These Cossacks became known as Kuban cossacks. A part of the Zaporozhian Cossacks escaped to beyond the Danube to become vassals of the Ottoman Sultan. They dwelt at mouth of the Danube river. In 1830 many of these Cossacks moved and established a new Sich on the Azov sea shore (between Mariupol and Berdiansk).  The last Kosh Otaman (leader) of Zaporizhian Sich Petro Kalnyshevsky was imprisoned at Solovetsky Island Monastery. At that time he was 85 years old. After 25 years in prison he was released and died almost blind at the monastery at age of 113 years.  In 1789, Danzig Mennonites from Prussia were invited by the czar to form settlements on the vast steppes of the Russian Empire. One of these settlements was located on the island of Khortytsia. They farmed on the rich island soil. Some of their profitable business was trade in lumber from the Khortytsia groves and woods. In 1916 the Mennonite colonists sold Khortytsia Island to the Olexandrivsk (Alexandrovsk) city council (see Chortitza Colony).  In 1965 Khortytsia Island was "proclaimed a historical and cultural reserve". The Dnieper Rapids state historical and cultural reserve was established in 1974; this included both Khortytsia Island, adjacent islands and rocks and part of the right bank of the Dnieper. The total area of the reserve is. The reserve was given national status in 1993.

National Reserve.

The major part of the reserve (historic park) covers the Zaporizhian Cossack Museum that includes the Cossack horse show. The museum building is modern, nestling low in the landscape with dramatic views of the Dnieper Hydroelectric Station to the north. The museum was built on October 14, 1983 as the Museum of Zaporizhia History although its project was approved by the Ministry of Culture and Derzhbud of Ukraine in December 1970. The expo area of the museum was accounted for portraying the following themes: Khortytsia in ancient times, history of Zaporizhian Cossacks, history of Zaporizhia at times of construction of socialism. There also existed four dioramas: "Battle of Sviatoslav at rapids" (author - M.Oviechkin), "Uprising of the impoverished cossacks at Zaporizhian Sich in 1768" (M.Oviechkin), "Construction of Dnieper HES" (V.Trotsenko), "Night storm of Zaporizhia city in October 1943" (M.Oviechkin). Part of the museum became also the Zaporizhian Oak located at the Upper Khortytsia. In 1992 the exposition of the museum was redesigned.  The museum contains exhibits dating from the Stone Age through the Scythian period (c.750 - 250 BC) down to the 20th century.

Other objects.

On Khortytsia at Savutyn summit close to the same name the ravine is a 74.5m tall three electrical transmission towers, called Zaporizhzhia Pylon Triple, which is a part of a 150 kV powerline crossing Dnieper river.

Khortytsia (, ; ; ) is the largest island in the River Dnieper, and is long and up to wide. The island forms part of the Khortytsya National Park. This historic site is located within the city limits of Zaporizhia, Ukraine.

Chortycja (ukrajinsky Хортиця) je největší ostrov na řece Dněpr. Nachází se na jižní Ukrajině na území města Záporoží. Ostrov má protáhlý tvar (od severozápadu k jihovýchodu), je přes 12 km dlouhý, střední šířka je přibližně 2,5 km.


Legendary biography.

Aside from a poetical account of Croesus on the pyre in Bacchylides (composed for Hiero of Syracuse, who won the chariot race at Olympia in 468), there are three classical accounts of Croesus: Herodotus presents the Lydian accounts of the conversation with Solon ("Histories" 1.29–33), the tragedy of Croesus' son Atys ("Histories" 1.34–45) and the fall of Croesus ("Histories" 1.85–89); Xenophon instances Croesus in his panegyric fictionalized biography of Cyrus: "Cyropaedia", 7.1; and Ctesias, whose account is also an encomium of Cyrus. Croesus is a descendant of Gyges, of the Myrmnadae Clan, who seized power when Gyges killed Candaules after Candaules's wife found out about a conspiracy to watch her disrobe, according to Herodotus.

Early rule and wealth.

Reportedly, Croesus on the death of his father Alyattes faced a rival claimant to the throne in Pantaleon, son of Alyattes by a different mother. Croesus prevailed, and a number of the opposing faction were executed, and their property confiscated. As soon as his reign was secure, Croesus continued his sires' wars against the Asian Greeks, bringing all the Aeolian and Ionian Settlements on the coasts of Asia-Minor under Lydian rule, from whom he exacted tribute; However, he was willing to be friendly to European and Aegean Greeks, concluding various treaties with them, with Sparta, in particular, later in life.  Croesus is credited with issuing the first true gold coins with a standardised purity for general circulation, the Croeseid (following on from his father Alyattes who invented minting with electrum coins). Indeed, the invention of coinage had passed into Greek society through Hermodike II. Hermodike II was likely one of Alyettes’ wives so may have been Croesus’ mother because the bull imagery on the croeseid symbolises the Hellenic Zeus – see Europa (consort of Zeus). Zeus, through Hercules, was the divine forefather of his family line.The dynasty which preceded that of Croesus on the throne of Sardes traced their descent from Alcaeus, the son of Hercules by Omphale, Queen of Lydia, during her year of required servitude. Like his ancestor Hercules, Croesus attempted to burn himself on a pyre when the Persians captured Sardes. By emulating the Greek myth, he demonstrated he had – or believed he had – Greek heritage.  Moreover, the first coins were quite crude and made of electrum, a naturally occurring pale yellow alloy of gold and silver. The composition of these first coins was similar to alluvial deposits found in the silt of the Pactolus river (made famous by Midas), which ran through the Lydian capital, Sardis. Later coins, including some in the British Museum, were made from gold purified by heating with common salt to remove the silver.  In Greek and Persian cultures the name of Croesus became a synonym for a wealthy man. He inherited great wealth from his father who had become associated with the Midas mythology because Lydian precious metals came from the river Pactolus in which King Midas supposedly washed away his ability to turn all he touched into gold. Aylettes’ tax revenue may be the real ‘Midas touch’ financing his and Croesus conquests. Croesus' wealth remained proverbial beyond classical antiquity: in English, expressions such as "rich as Croesus" or "richer than Croesus" are used to indicate great wealth to this day. The earliest known such usage in English was John Gower's in "Confessio amantis" (1390):  Original text: Modern spelling:

Interview with Solon.

According to Herodotus, Croesus encountered the Greek sage Solon and showed him his enormous wealth. Croesus, secure in his own wealth and happiness, asked Solon who the happiest man in the world was, and was disappointed by Solon's response that three had been happier than Croesus: Tellus, who died fighting for his country, and the brothers Kleobis and Biton who died peacefully in their sleep after their mother prayed for their perfect happiness because they had demonstrated filial piety by drawing her to a festival in an oxcart themselves. Solon goes on to explain that Croesus cannot be the happiest man because the fickleness of fortune means that the happiness of a man's life cannot be judged until after his death. Sure enough, Croesus' hubristic happiness was reversed by the tragic deaths of his accidentally-killed son and, according to Critias, his wife's suicide at the fall of Sardis, not to mention his defeat at the hands of the Persians.  The interview is in the nature of a philosophical disquisition on the subject "Which man is happy?" It is legendary rather than historical. Thus the "happiness" of Croesus is presented as a moralistic "exemplum" of the fickleness of Tyche, a theme that gathered strength from the fourth century, revealing its late date. The story was later retold and elaborated by Ausonius in "The Masque of the Seven Sages", in the "Suda" (entry "Μᾶλλον ὁ Φρύξ," which adds Aesop and the Seven Sages of Greece), and by Tolstoy in his short story "Croesus and Fate".

Croesus' votive offerings to Delphi.

According to Herodotus, Croesus desired to discover which of the well known oracles of his time gave trustworthy omens. He sent ambassadors to the most important oracles ordering that on the 100th day from their departure from Sardis they should ask what the king of the Lydians, Croesus, son of Alyattes was doing on this exact date. Then on the 100th day the envoys entered the oracle of Delphi in order to ask for the omen, the Pythia answered in verse:  The envoys wrote down the answer and returned to Sardis. Croesus read all the answers brought by his envoys from all the oracles. As soon as he read the answer of the Pythia he bowed, because he was persuaded that it was the only real oracle, along with that of Amphiaraus. Indeed, on the specific date Croesus had put pieces of a tortoise and lamb to boil together in a bronze cauldron, covered with a bronze lid. Then, Croesus wanted to thank and take on his side the oracle of Delphi. He sacrificed three thousand of all kinds of sacrificial animals. Then he lit a bonfire and burned precious objects. After the sacrifice he melted down gold and made golden blocks, each one 2.5 talents. He ordered his artists to make the copy of a lion out of pure gold, weighing ten talents. At the time of Herodotus this was situated at the Treasury of the Corinthians in Delphi, but 3.5 talents lighter, as the priests had melted down part of it. Croesus also sent along two enormous "krateres" (wine-mixing bowls), one made of gold and one made of silver, situated on one side and the other of the entrance to the temple of Apollo. After the fire which destroyed the temple, these "krateres" were transferred elsewhere: the golden one was transferred to the treasury of the Klazomenians, whereas the silver one was placed again in the vestibule of the new temple. Within this "krater" took place the mixing of water and wine during the Theophania. In Delphi they used to say that this one had been made by Theodorus of Samos. The votive offerings of Croesus comprised also four silver "pithoi" (storage jars), situated at the Treasury of the Corinthians, and two "perirrhanteria" (basins for purification water) made of precious metals and a statue of a woman made of gold; they said that it depicted the woman who kneaded Croesus' bread. Finally, he dedicated the pendants and belts of his wife as well as other simpler and smaller liturgical objects and a golden shield which he offered to the Archaic temple of Athena Pronaia, later on melted by the Phocians in the course of the Third Sacred War.

Death of son.

According to legend, Croesus gave refuge at one point to the Phrygian prince Adrastus. Herodotus tells that Adrastus exiled himself to Lydia after accidentally killing his brother. Croesus later experienced a dream for which he took as prophecy in which Atys, his son and heir, would be killed by an iron spearhead. Taking precautions against this, Croesus kept his son from leading in military expeditions and fighting in any way. However, according to Herodotus, a wild boar began to ravage the neighboring province of Mysia, which soon begged Croesus to send a military expedition led by Atys to kill the boar. Croesus thought this would be safe for his son, as Atys would not be fighting an enemy that could throw a spear. However, he sent Adrastus with Atys as a bodyguard in case they might be waylaid by bandits on the expedition. While fighting the boar, Adrastus accidentally hit Atys with his spear, killing him. Croesus absolved Adrastus for his son's death; however, Adrastus later committed suicide.

Campaign against Persia and testing of oracle.

Croesus' uneasy relations with the Ionian Greeks obscures the larger fact that he was the last bastion of the Ionian cities against the increasing Persian power in Anatolia. He began preparing a campaign against Cyrus the Great of Persia.  Before setting out, he turned to the Delphic oracle and the oracle of Amphiaraus to inquire whether he should pursue this campaign and whether he should also seek an alliance. The oracles answered, with typical ambiguity, that if Croesus attacked the Persians, he would destroy a great empire (ἢν στρατεύηται ἐπὶ Πέρσας, μεγάλην ἀρχὴν μιν καταλύσειν) – this would become one of the most famous oracular statements from Delphi.  The oracles also advised Croesus to find out which Greek state was most powerful and to ally himself with it. Croesus, now feeling secure, formed an alliance with Sparta in addition to those he had with Amasis II of Egypt and Nabonidus of Babylonia, and launched his campaign against the Persian Empire in 547 BC. (The scholar Evans in 1978 examines the conflicting dates implied in Herodotus.) Croesus was intercepted near the Halys River in central Anatolia and an inconclusive battle was fought at Pteria. It was the usual practice in those days for the armies to disband for winter and Croesus did so accordingly. Cyrus did not, however, and he attacked and defeated Croesus in Thymbria and later in Sardis, eventually capturing him. It became clear that the powerful empire destroyed by the war was Croesus's own.

Rescue from death and advisor to Cyrus.

By 546 BC, Croesus was defeated at the Battle of Thymbra under the wall of his capital city of Sardis. After the Siege of Sardis, he was then captured by the Persians. According to various accounts of Croesus's life, Cyrus ordered him to be burned to death on a pyre, but Croesus escaped death. Accounts of his escape vary considerably:  In Bacchylides' ode, Croesus with his wife and family mounted the funeral pyre, but before the flames could envelop the king, he was snatched up by Apollo and spirited away to the Hyperboreans. Herodotus tells us that in the Lydian account, Croesus was placed upon a great pyre by Cyrus' orders, for Cyrus wanted to see if any of the heavenly powers would appear to save him from being burned alive. The pile was set ablaze, and as Cyrus the Great watched he saw Croesus call out "Solon" three times. He asked the interpreters to find out why he said this word with such resignation and agony. The interpreters returned the answer that Solon had warned Croesus of the fickleness of good fortune (see Interview with Solon above). This touched Cyrus, who realized that he and Croesus were much the same man, and he bade the servants to quench the blazing fire as quickly as they could. They tried to do this, but the flames were not to be mastered. According to the story, Croesus called out to Apollo and prayed to him. The sky had been clear and the day without a breath of wind, but soon dark clouds gathered and a storm with rain of such violence that the flames were speedily extinguished. Cyrus, thus convinced that Croesus was a good man, made him an advisor who served Cyrus "well" and later Cyrus's son by Cassandane, Cambyses.  "The Cambridge History of Iran" argues that there is no evidence that Cyrus the Great killed Croesus, and in particular rejects the account of burning on a pyre. It interprets Bacchylides' narration as Croesus attempting suicide and then being saved by Cyrus.  Recently, Stephanie West has argued that the historical Croesus did in fact die on the pyre, and that the stories of him as a wise advisor to the courts of Cyrus and Cambyses are purely legendary, showing similarities to the sayings of Ahiqar.  After defeating Croesus, the Persians adopted gold as the main metal for their coins.

Death.

It is not known when exactly Croesus died, although it could be aligned with the traditional date for Cyrus' conquest of Lydia in 546 BC. In the Nabonidus Chronicle it is said that Cyrus "marched against the country –, killed its king, took his possessions, put there a garrison of his own". Unfortunately, all that remains of the name of the country are traces of the first cuneiform sign. It has long been assumed that this sign should be LU, so that the country referred to would be Lydia, with Croesus as the king that was killed. However, J. Cargill has shown that this restoration was based upon wishful thinking rather than actual traces of the sign LU. Instead, J. Oelsner and R. Rollinger have both read the sign as Ú, which might imply a reference to Urartu. With Herodotus' account also being unreliable chronologically in this case, as J. A. S. Evans has demonstrated, this means that we currently have no way of dating the fall of Sardis; theoretically, it may even have taken place after the fall of Babylon in 539 BC. Evans also asks what happened after the episode at the pyre and suggests that "neither the Greeks nor the Babylonians knew what really happened to Croesus".

In popular culture.

References to Croesus' legendary power and wealth, often as a symbol of human vanity, are numerous in literature. The following, by Isaac Watts, is from the poem titled "False Greatness":  Other literary examples are "Croesus and Fate", a short story by Leo Tolstoy that is a retelling of the account of Croesus as told by Herodotus and Plutarch; and "Crœsus, King of Lydia", a tragedy in five parts by Alfred Bate Richards, first published in 1845. "The Last King of Lydia", and "The King and The Slave", both by Tim Leach, are historical novels centered around Croesus and based primarily on Herodotus' depiction of his life, before and after the fall of Lydia.  In The Simpsons season 3 episode 19 the street signs show Mr. Burns' estate on the corner of Croesus and Mammon

Croesus ( ;, "Kroisos"; 595 BC – date of death unknown) was the king of Lydia who, according to Herodotus, reigned for 14 years: from 560 BC until his defeat by the Persian king Cyrus the Great in 546 BC (sometimes given as 547 BC).

Kroisos (řecky "Κροῖσος", latinsky "Croesus") byl lýdský král z rodu Mermnovců, panující asi v letech 560–547 př. n. l. Byl synem krále Alyatta II. a blíže neznámé ženy z kárského rodu. Podle antických pramenů měl několik nevlastních bratrů a sester.


Definition.

The term "chess problem" is not sharply defined: there is no clear demarcation between chess compositions on the one hand and puzzles or tactical exercises on the other. In practice, however, the distinction is very clear. There are common characteristics shared by compositions in the problem section of chess magazines, in specialist chess problem magazines, and in collections of chess problems in book form.

Features.

Not every chess problem has every one of these features, but most have several:

Tactical puzzles.

Problems can be contrasted with tactical puzzles often found in chess columns or magazines in which the task is to find the best move or sequence of moves (usually leading to mate or gain of material) from a given position. Such puzzles are often taken from actual games, or at least have positions which look as if they could have arisen during a game, and are used for instructional purposes. Most such puzzles fail to exhibit the above features.

Types of problems.

There are various different types of chess problems:  In all the above types of problem, castling is assumed to be allowed unless it can be proved by retrograde analysis (see below) that the rook in question or king must have previously moved. "En passant" captures, on the other hand, are assumed "not" to be legal, unless it can be proved that the pawn in question must have moved two squares on the previous move.  There are several other types of chess problem which do not fall into any of the above categories. Some of these are really coded mathematical problems, expressed using the geometry and pieces of the chessboard. A famous such problem is the knight's tour, in which one is to determine the path of a knight that visits each square of the board exactly once. Another is the eight queens problem, in which eight queens are to be placed on the board so that none is attacking any of the others.  Of far greater relation to standard chess problems, however, are the following, which have a rich history and have been revisited many times, with magazines, books and prizes dedicated to them:  Across most of the above genres, there is great interest in exploring Fairy chess: where non-standard boards, pieces or rules apply.

Beauty in chess problems.

The role of aesthetic evaluation in the appreciation of chess problems is very significant, and indeed most composers and solvers consider such compositions to be an art form. Vladimir Nabokov wrote about the "originality, invention, conciseness, harmony, complexity, and splendid insincerity" of creating chess problems and spent considerable time doing so. There are no official standards by which to distinguish a beautiful problem from a poor one and such judgments can vary from individual to individual as well as from generation to generation. Such variation is to be expected when it comes to aesthetic appraisal. Nevertheless, modern taste generally recognises the following elements to be important in the aesthetic evaluation of a problem:

Example problem.

To the right is a directmate problem composed by Thomas Taverner in 1881.  The key move is 1.Rh1. This is difficult to find because it makes no threat – instead, it puts Black in zugzwang, a situation in which every move leads to a disadvantage, yet the player must move. Each of Black's nineteen legal replies allows an immediate mate. For example, if Black defends with 1...Bxh7, the d5 square is no longer guarded, and White mates with 2.Nd5#. Or if Black plays 1...Re5, Black blocks that escape square for his king allowing 2.Qg4#. If Black plays 1...Rf6, then 2.Rh4#. Yet if Black could only pass (i.e., make no move at all), White would have no way to mate on his second move.  The thematic approach to solving is to notice then that in the original position, Black is already almost in zugzwang. If Black were compelled to play first, only Re3 and Bg5 would not allow immediate mate. However, each of those two moves blocks a flight square for the black king, and once White has removed his rook from h2 White can put some other piece on that square to deliver mate: 1...Re3 2.Bh2# and 1...Bg5 2.Qh2#.  The arrangement of the black rooks and bishops, with a pair of adjacent rooks flanked by a pair of bishops, is known to problemists as Organ Pipes. This arrangement is designed to illustrate the effect of mutual Black interferences: for example, consider what happens after the key if Black plays 1...Bf7. White now mates with 2.Qf5#, a move which is only possible because the bishop Black moved has got in the way of the rook's guard of f5 – this is known as a "self-interference". Similarly, if Black tries 1...Rf7, this interferes with the bishop's guard of d5, allowing White to mate with Nd5#. Mutual interferences like this, between two pieces on one square, are known as Grimshaw interferences. The theme this problem exhibits is precisely such Grimshaw interferences.

Abbreviations.

For reasons of space and internationality, various abbreviations are often used in chess problem journals to indicate a problem's stipulation (whether it is a mate in two, helpmate in four, or whatever). The most common are:  These are combined with a number to indicate how many moves the goal must be achieved in. "#3", therefore, indicates a mate in three, while "ser-h=14" indicates a series help stalemate in 14 (i.e., Black makes 14 moves in a row such that White can subsequently make one move to deliver stalemate).  In studies, the symbols "+" and "=" are used to indicate "White to play and win" and "White to play and draw" respectively.

Tournaments.

Various tournaments (or "tourneys") exist for both the composition and solving of chess problems.

Composition tournaments.

Composition tourneys may be "formal" or "informal". In formal tourneys, the competing problems are not published before they are judged, while in informal tourneys they are. Informal tourneys are often run by problem magazines and other publications with a regular problem section; it is common for every problem to have been published in a particular magazine within a particular year to be eligible for an informal award. Formal tourneys are often held to commemorate a particular event or person. The World Chess Composing Tournament (WCCT) is a formal tourney for national teams organised by the Permanent Commission of the FIDE for Chess Compositions (PCCC).  In both formal and informal tourneys, entries will normally be limited to a particular genre of problem (for example, mate in twos, moremovers, helpmates) and may or may not have additional restrictions (for example, problems in patrol chess, problems showing the Lacny theme, problems using fewer than nine units). Honours are usually awarded in three grades: these are, in descending order of merit, prizes, honourable mentions, and commendations. As many problems as the judge sees fit may be placed in each grade, and the problems within each grade may or may not be ranked (so an award may include a 1st Honourable Mention, a 2nd Honourable Mention, and a 3rd Honourable Mention, or just three unranked Honourable Mentions).  After an award is published, there is a period (typically around three months) in which individuals may claim honoured problems are "anticipated" (that is, that an identical problem, or nearly so, had been published at an earlier date) or unsound (i.e., that a problem has cooks or no solution). If such claims are upheld, the award may be adjusted accordingly. At the end of this period, the award becomes final. It is normal to indicate any honour a problem has received when it is republished.

Solving tournaments.

Solving tournaments also fall into two main types. In tourneys conducted by correspondence, the participants send their entries by post or e-mail. These are often run on similar terms to informal composition tourneys; indeed, the same problems which are entries in the informal composition tourney are often also set in the solving tourney. It is impossible to eliminate the use of computers in such tournaments, though some problems, such as those with particularly long solutions, will not be well-suited to solution by computer.  Other solving tourneys are held with all participants present at a particular time and place. They have only a limited amount of time to solve the problems, and the use of any solving aid other than a chess set is prohibited. The most notable tournament of this type is the World Chess Solving Championship, organised by the PCCC.  In both types of tourney, each problem is worth a specified number of points, often with bonus points for finding cooks or correctly claiming no solution. Incomplete solutions are awarded an appropriate proportion of the points available. The solver amassing the most points is the winner.

Titles.

Just as in over-the-board play, the titles International Grandmaster, International Master and FIDE Master are awarded by FIDE via the Permanent Commission of the FIDE for Chess Compositions (PCCC) for especially distinguished problem and study composers and solvers (unlike over-the-board chess, however, there are no women-only equivalents to these titles in problem chess).  For composition, the International Master title was established in 1959, with André Chéron, Arnoldo Ellerman, Alexander Gerbstmann, Jan Hartong, Cyril Kipping and Marian Wróbel being the first honorary recipients. In subsequent years, qualification for the IM title, as well as for the GM title (first awarded in 1972 to Genrikh Kasparyan, Lev Loshinsky, Comins Mansfield, and Eeltje Visserman) and the FM title (first awarded 1990) has been determined on the basis of the number of problems or studies a composer had selected for publication in the FIDE Albums. These albums are collections of the best problems and studies composed in a particular three-year period, as selected by FIDE-appointed judges from submitted entries. Each problem published in an album is worth 1 point; each study is worth 12⁄3; joint compositions are worth the same divided by the number of composers. For the FIDE Master title, a composer must accumulate 12 points; for the International Master title, 25 points are needed; and for the Grandmaster title, a composer must have 70 points.  For solvers, the GM and IM titles were both first awarded in 1982; the FM title followed in 1997. GM and IM titles can only be gained by participating in the official World Chess Solving Championship (WCSC): to become a GM, a solver must score at least 90 percent of the winner's points and on each occasion finish in at least tenth place three times within ten successive WCSCs. For the IM title they must score at least 80 percent of the winner's points and each time finish in at least fifteenth place twice within five successive WCSCs; alternatively, winning a single WCSC or scoring as many points as the winner in a single WCSC will earn the IM title. For the FM title, the solver must score at least 75 percent of the winners points and each time finish within the top 40 percent of participants in any two PCCC-approved solving competitions.  The title International Judge of Chess Compositions is given to individuals considered capable of judging composing tourneys at the highest level.

A chess problem, also called a chess composition, is a puzzle set by the composer using chess pieces on a chess board, which presents the solver with a particular task. For instance, a position may be given with the instruction that White is to move first, and checkmate Black in two moves against any possible defence. A chess problem fundamentally differs from over-the-board play in that the latter involves a struggle between black and white, whereas the former involves a competition between the composer and the solver. Most positions which occur in a chess problem are 'unrealistic' in the sense that they are very unlikely to occur in over-the-board play. There is a good deal of specialized jargon used in connection with chess problems; see glossary of chess problems for a list.

Kompoziční šach či problémový šach je samostatné šachové odvětví, týkající se skládání a řešení "šachových skladeb" (zvaných též šachové problémy nebo kompozice). Šachová skladba je obvykle tvořena umělou "šachovou pozicí" a "výzvou". Podle výzvy se šachové kompozice dělí na úlohy a studie.


Morphology.

Members of the Collembola are normally less than long, have six or fewer abdominal segments, and possess a tubular appendage (the collophore or ventral tube) with reversible, sticky vesicles, projecting ventrally from the first abdominal segment. It is believed to be associated with fluid uptake and balance, excretion, and orientation of the organism itself. Most species have an abdominal, tail-like appendage known as a furcula. It is located on the fourth abdominal segment of collembolans and is folded beneath the body, held under tension by a small structure called the retinaculum (or tenaculum). When released, it snaps against the substrate, flinging the springtail into the air and allowing for rapid evasion and migration. All of this takes place in as little as 18 milliseconds.  Springtails also possess the ability to reduce their body size by as much as 30% through subsequent ecdyses (molting) if temperatures rise high enough. The shrinkage is genetically controlled. Since warmer conditions increase metabolic rates and energy requirements in organisms, the reduction in body size is advantageous to their survival.  The Poduromorpha and Entomobryomorpha have an elongated body, while the Symphypleona and Neelipleona have a globular body. Collembola lack a tracheal respiration system, which forces them to respire through a porous cuticle, with the notable exception of the Sminthuridae, which exhibit a rudimentary, although fully functional, tracheal system.The anatomical variance present between different species partially depends on soil morphology and composition. Surface-dwellers are generally larger, have darker pigments, have longer antennae and functioning furcula. Sub-surface-dwellers, are usually unpigmented, have elongated bodies, and reduced furcula. They can be categorized into four main forms according to soil composition and depth: atmobiotic, epedaphic, hemiedaphic, and euedaphic. Atmobiotic species inhabit macrophytes and litter surfaces. They are generally 8-10 millimeters in length, pigmented, have long limbs, and a full set of ocelli (photoreceptors). Epedaphic species inhabit upper litter layers and fallen logs. They are slightly smaller and have less pronounced pigments, as well as less developed limbs and ocelli than the atmobiotic species. Hemiedaphic species inhabit the lower litter layers of decomposing organic material. They are 1-2 millimeters in length, have dispersed pigmentation, shortened limbs, and a reduced number of ocelli. Euedaphic species inhabit upper mineral layers known as the humus horizon. They are smaller than hemiedaphic species; have soft, elongated bodies; lack pigmentation and ocelli; and have reduced or absent furca.  Poduromorphs inhabit the epedaphic, hemiedaphic, and euedaphic layers and are characterized by their elongated bodies and conspicuous segmentation – three thoracic segments, six abdominal segments, and a prothorax.  The digestive tract of collembolan species consists of three main components: the foregut, midgut, and hindgut. The midgut is surrounded by a network of muscles and lined with a monolayer of columnar or cuboidal cells. Its function is to mix and transport food from the lumen into the hindgut through contraction. Many species of syntrophic bacteria, archaea, and fungi are present in the lumen. These different digestive regions have varying pH to support specific enzymatic activities and microbial populations. The anterior portion of the midgut and hindgut is slightly acidic (with a pH of approximately 6.0) while the posterior midgut portion is slightly alkaline (with a pH of approximately 8.0). Between the midgut and hindgut is an alimentary canal called the pyloric region, which is a muscular sphincter.

Systematics and evolution.

Traditionally, the springtails were divided into the orders Arthropleona, Symphypleona, and occasionally also Neelipleona. The Arthropleona were divided into two superfamilies, the Entomobryoidea and the Poduroidea, but actually, these two and the Symphypleona form three lineages, each of which is equally distant from the other two. Thus, the Arthropleona are abolished in modern classifications, and their superfamilies are raised in rank accordingly, being now the Entomobryomorpha and the Poduromorpha. Technically, the Arthropleona are thus a partial junior synonym of the Collembola. The term "Neopleona" is essentially synonymous with Symphypleona + Neelipleona.  The Neelipleona was originally seen as a particularly advanced lineage of Symphypleona, based on the shared global body shape, but the global body of the Neelipleona is realized in a completely different way than in Symphypleona. Subsequently, the Neelipleona were considered as being derived from the Entomobryomorpha. Analysis of 18S and 28S rRNA sequence data, though, suggests that they form the most ancient lineage of springtails, which would explain their peculiar apomorphies.  Springtails are attested to since the Early Devonian. The fossil from, "Rhyniella praecursor", is the oldest terrestrial arthropod, and was found in the famous Rhynie chert of Scotland. Given its morphology resembles extant species quite closely, the radiation of the Hexapoda can be situated in the Silurian, or more. Additional research concerning the coprolites (fossilized feces) of ancient collembolans allowed researchers to track their lineages back some 412 million years.  Fossil Collembola are rare. Instead, most are found in amber. Even these are rare and many amber deposits carry few or no collembola. The best deposits are from the early Eocene of Canada and Europe, Miocene of Central America, and the mid-Cretaceous of Burma and Canada. They display some unexplained characteristics: first, all but one of the fossils from the Cretaceous belong to extinct genera, whereas none of the specimens from the Eocene or the Miocene are of extinct genera; second, the species from Burma are more similar to the modern fauna of Canada than are the Canadian Cretaceous specimens.  There are about 3,600 different species.

Ecology.

Eating behavior.

Specific feeding strategies and mechanisms are employed to match specific niches. Herbivorous and detritivorous species fragment biological material present in soil and leaf litter, supporting decomposition and increasing the availability of nutrients for various species of microbes and fungi. Carnivorous species maintain populations of small invertebrates such as nematodes, rotifers, and other collembolan species. Springtails commonly consume fungal hyphae and spores, but also have been found to consume plant material and pollen, animal remains, colloidal materials, minerals and bacteria.

Distribution.

Springtails are cryptozoa frequently found in leaf litter and other decaying material, where they are primarily detritivores and microbivores, and one of the main biological agents responsible for the control and the dissemination of soil microorganisms. In a mature deciduous woodland in temperate climate, leaf litter and vegetation typically support 30 to 40 species of springtails, and in the tropics the number may be over 100.  In sheer numbers, they are reputed to be one of the most abundant of all macroscopic animals, with estimates of 100,000 individuals per square meter of ground, essentially everywhere on Earth where soil and related habitats (moss cushions, fallen wood, grass tufts, ant and termite nests) occur. Only nematodes, crustaceans, and mites are likely to have global populations of similar magnitude, and each of those groups except mites is more inclusive: though taxonomic rank cannot be used for absolute comparisons, it is notable that nematodes are a phylum and crustaceans a subphylum. Most springtails are small and difficult to see by casual observation, but one springtail, the so-called snow flea ("Hypogastrura nivicola"), is readily observed on warm winter days when it is active and its dark color contrasts sharply with a background of snow.  In addition, a few species routinely climb trees and form a dominant component of canopy faunas, where they may be collected by beating or insecticide fogging. These tend to be the larger (>2 mm) species, mainly in the genera "Entomobrya" and "Orchesella", though the densities on a per square meter basis are typically 1–2 orders of magnitude lower than soil populations of the same species. In temperate regions, a few species (e.g. "Anurophorus" spp., "Entomobrya albocincta", "Xenylla xavieri", "Hypogastrura arborea") are almost exclusively arboreal. In tropical regions a single square meter of canopy habitat can support many species of Collembola.  The main ecological factor driving the local distribution of species is the vertical stratification of the environment: in woodland a continuous change in species assemblages can be observed from tree canopies to ground vegetation then to plant litter down to deeper soil horizons. This is a complex factor embracing both nutritional and physiological requirements, together with behavioural trends, dispersal limitation and probable species interactions. Some species have been shown to exhibit negative or positive gravitropism, which adds a behavioural dimension to this still poorly understood vertical segregation. Experiments with peat samples turned upside down showed two types of responses to disturbance of this vertical gradient, called "stayers" and "movers".  As a group, springtails are highly sensitive to desiccation, because of their tegumentary respiration, although some species with thin, permeable cuticles have been shown to resist severe drought by regulating the osmotic pressure of their body fluid. The gregarious behaviour of Collembola, mostly driven by the attractive power of pheromones excreted by adults, gives more chance to every juvenile or adult individual to find suitable, better protected places, where desiccation could be avoided and reproduction and survival rates (thereby fitness) could be kept at an optimum. Sensitivity to drought varies from species to species and increases during ecdysis. Given that springtails moult repeatedly during their entire life (an ancestral character in Hexapoda) they spend much time in concealed micro-sites where they can find protection against desiccation and predation during ecdysis, an advantage reinforced by synchronized moulting. The high humidity environment of many caves also favours springtails and there are numerous cave adapted species, including one, "Plutomurus ortobalaganensis" living down the Krubera Cave.  The horizontal distribution of springtail species is affected by environmental factors which act at the landscape scale, such as soil acidity, moisture and light. Requirements for pH can be reconstructed experimentally. Altitudinal changes in species distribution can be at least partly explained by increased acidity at higher elevation. Moisture requirements, among other ecological and behavioural factors, explain why some species cannot live aboveground, or retreat in the soil during dry seasons, but also why some epigeal springtails are always found in the vicinity of ponds and lakes, such as the hygrophilous "Isotomurus palustris". Adaptive features, such as the presence of a fan-like wettable mucro, allow some species to move at the surface of water ("Sminthurides aquaticus", "Sminthurides malmgreni"). "Podura aquatica", a unique representative of the family Poduridae (and one of the first springtails to have been described by Linnaeus), spends its entire life at the surface of water, its wettable eggs dropping in water until the non-wettable first instar hatches then surfaces.  In a variegated landscape, made of a patchwork of closed (woodland) and open (meadows, cereal crops) environments, most soil-dwelling species are not specialized and can be found everywhere, but most epigeal and litter-dwelling species are attracted to a particular environment, either forested or not. As a consequence of dispersal limitation, landuse change, when too rapid, may cause the local disappearance of slow-moving, specialist species, a phenomenon the measure of which has been called colonisation credit.

Relationship with humans.

Springtails are well known as pests of some agricultural crops. "Sminthurus viridis", the lucerne flea, has been shown to cause severe damage to agricultural crops, and is considered as a pest in Australia. Onychiuridae are also known to feed on tubers and to damage them to some extent. However, by their capacity to carry spores of mycorrhizal fungi and mycorrhiza helper bacteria on their tegument, soil springtails play a positive role in the establishment of plant-fungal symbioses and thus are beneficial to agriculture. They also contribute to controlling plant fungal diseases through their active consumption of mycelia and spores of damping-off and pathogenic fungi. It has been suggested that they could be reared to be used for the control of pathogenic fungi in greenhouses and other indoor cultures.  Various sources and publications have suggested that some springtails may parasitize humans, but this is entirely inconsistent with their biology, and no such phenomenon has ever been scientifically confirmed, though it has been documented that the scales or hairs from collembolans can cause irritation when rubbed onto the skin. They may sometimes be abundant indoors in damp places such as bathrooms and basements, and incidentally found on one's person. More often, claims of persistent human skin infection by springtails may indicate a neurological problem, such as delusory parasitosis, a psychological rather than entomological problem. Researchers themselves may be subject to psychological phenomena. For example, a publication in 2004 claiming that springtails had been found in skin samples was later determined to be a case of pareidolia; that is, no springtail specimens were actually recovered, but the researchers had digitally enhanced photos of sample debris to create images resembling small arthropod heads, which then were claimed to be springtail remnants. However, Steve Hopkin reports one instance of an entomologist aspirating an "Isotoma" species and in the process accidentally inhaling some of their eggs, which hatched in his nasal cavity and made him quite ill until they were flushed out.  Although firmly denied by the US government despite the existence of the Pine Bluff Arsenal of biological weapons, destroyed in 1971–1972 under Nixon’s presidency, it has been reported that springtails were used by the US army as a "six-legged weapon" in biological warfare performed during the Korean War. Species cited in allegations of biological warfare in the Korean War were "Isotoma (Desoria) negishina" (a local species) and the "white rat springtail" "Folsomia candida". According to these reports, isotomids were intended to serve as carriers of fatal diseases (anthrax, dysentery, cholera, small pox), dropped by airplanes above rebel villages.  Captive springtails are often kept in a terrarium as part of a clean-up crew.

Ecotoxicology laboratory animals.

Springtails are currently used in laboratory tests for the early detection of soil pollution. Acute and chronic toxicity tests have been performed by researchers, mostly using the parthenogenetic isotomid "Folsomia candida". These tests have been standardized. Details on a ringtest, on the biology and ecotoxicology of "Folsomia candida" and comparison with the sexual nearby species "Folsomia fimetaria" (sometimes preferred to "Folsomia candida") are given in a document written by Paul Henning Krogh. Care should be taken that different strains of the same species may be conducive to different results. Avoidance tests have been also performed. They have been standardized, too. Avoidance tests are complementary to toxicity tests, but they also offer several advantages: they are more rapid (thus cheaper), more sensitive and they are environmentally more reliable, because in the real world Collembola move actively far from pollution spots. It may be hypothesized that the soil could become locally depauperated in animals (and thus improper to normal use) while below thresholds of toxicity. Contrary to earthworms, and like many insects and molluscs, Collembola are very sensitive to herbicides and thus are threatened in no-tillage agriculture, which makes a more intense use of herbicides than conventional agriculture. The springtail "Folsomia candida" is also becoming a genomic model organism for soil toxicology. With microarray technology the expression of thousands of genes can be measured in parallel. The gene expression profiles of "Folsomia candida" exposed to environmental toxicants allow fast and sensitive detection of pollution, and additionally clarifies molecular mechanisms causing toxicology.  Collembola have been found to be useful as bio-indicators of soil quality. Laboratory studies have been conducted that validated that the jumping ability of springtails can be used to evaluate the soil quality of Cu- and Ni-polluted sites.

Climate warming impact.

In polar regions that are expected to experience among the most rapid impact from climate warming, springtails have shown contrasting responses to warming in experimental warming studies. There are negative, positive and neutral responses reported. Neutral responses to experimental warming have also been reported in studies of non-polar regions. The importance of soil moisture has been demonstrated in experiments using infrared heating in an alpine meadow, which had a negative effect on mesofauna biomass and diversity in drier parts and a positive effect in moist sub-areas. Furthermore, a study with 20 years of experimental warming in three contrasting plant communities found that small scale heterogeneity may buffer springtails to potential climate warming.

Reproduction.

Sexual reproduction occurs through the clustered or scattered deposition of spermatophores by male adults. Stimulation of spermatophore deposition by female pheromones has been demonstrated in "Sinella curviseta". Mating behaviour can be observed in Symphypleona. Among Symphypleona, males of some Sminthuridae use a clasping organ located on their antenna. Many collembolan species, mostly those living in deeper soil horizons, are parthenogenetic, which favours reproduction to the detriment of genetic diversity and thereby to population tolerance of environmental hazards. Parthenogenesis (also called thelytoky) is under the control of symbiotic bacteria of the genus "Wolbachia", which live, reproduce and are carried in female reproductive organs and eggs of Collembola. Feminizing "Wolbachia" species are widespread in arthropods and nematodes, where they co-evolved with most of their lineages.

Springtails (Collembola) form the largest of the three lineages of modern hexapods that are no longer considered insects (the other two are the Protura and Diplura). Although the three orders are sometimes grouped together in a class called Entognatha because they have internal mouthparts, they do not appear to be any more closely related to one another than they are to all insects, which have external mouthparts.

Chvostoskoci (Collembola) jsou starobylá bazální skupina šestinohých (tj. hmyzu v širokém slova smyslu). Jsou to drobní živočichové žijící v půdě nebo na povrchu půdy, v humusu, opadu, někdy i na vodní hladině, firnových polích či okrajích ledovců. Jejich hlavním znakem (a synapomorfií) je unikátní skákací aparát a ventrální tubus na zadečku – "collophor". Označení Collembola pochází ze starořeckého κόλλα "kólla" „lepidlo“ a ἔμβολος "émbolos" „kolík“; toto označení plyne z existence collophora, jehož účel byl předpokládán v přilepení k povrchům a stabilizaci.


Background.

In 965 or 966, a Bulgarian embassy visited the Byzantine emperor Nikephoros II Phokas (r. 963–969) at Constantinople to receive the annual tribute that had been agreed by the two powers as the price of peace in 927. Phokas, flush and self-confident from a series of victories against the Arabs in the East that had led to the recovery of Crete, Cyprus, and Cilicia, refused to comply, and even had the envoys beaten up. He followed this up with a show of military strength, by sending a small force to raze a number of Bulgarian border posts in Thrace.  It was a clear declaration of war, but Nikephoros' forces were largely preoccupied in the East. Thus the emperor turned to the traditional Byzantine expedient of turning one of the peoples living further north, in modern-day Ukraine, against Bulgaria. He sent an ambassador, the "patrikios" Kalokyros, to Sviatoslav, ruler of the Rus' with whom the Byzantines had maintained close relations. Sviatoslav enthusiastically responded, and invaded Bulgaria in 967 or 968 in a devastating raid, before returning home to defend his capital against a Pecheneg attack. This forced the Bulgarian tsar, Peter I, to the negotiating table, agreeing to terms favourable to Byzantium. However, this brief sojourn also awakened in Sviatoslav the desire to conquer Bulgaria and establish his own realm there. He returned in force in July or August 969 and conquered the country within a few months.  Nikephoros' scheme had backfired dramatically: instead of peace, a new and formidable foe had appeared in the Balkans, and a large part of the Bulgarian nobility appeared to side with the Rus' prince. The emperor, however, was murdered in December 969, and it fell to his successor, John I Tzimiskes (r. 969–976), to deal with the Rus' threat. Sviatoslav now turned his sights on Byzantium, and to John's entreaties for peace he allegedly answered that the Empire should abandon its European territories to him and withdraw to Asia Minor. Tzimiskes himself was preoccupied with consolidating his position and with countering the unrest of the powerful Phokas clan and its adherents, and delegated the war in the Balkans to his brother-in-law, the Domestic of the Schools Bardas Skleros, and to the eunuch "stratopedarches" Peter. They were to winter in Thrace and raise an army, whilst sending spies to discover Sviatoslav's intentions.  At the news of this, a powerful Rus' force, along with many Bulgarians and a Pecheneg contingent, was sent south over the Balkan Mountains. After sacking the city of Philippopolis (modern Plovdiv) in Thrace, they bypassed the heavily defended city of Adrianople and turned towards Constantinople. The size of the Rus' army, and whether it comprised the entirety of Sviatoslav's forces or just a division, is unclear. John Skylitzes, for instance, implies that this was the entire Rus' army, numbering an incredible 308,000 men, but the contemporary Leo the Deacon reports that it was a detachment of "over 30,000 men"; conversely, the Russian "Primary Chronicle" gives the "entire" Rus' army under Sviatoslav at some 30,000, whilst numbering the Rus' at Arcadiopolis at only 10,000, faced with 100,000 Byzantines. It is clear, however, that the Byzantines were considerably outnumbered, and that the Rus' force at Arcadiopolis included significant numbers of Bulgarians, as well as allied contingents of Pechenegs and "Turks" (i.e. Magyars).

The battle.

Skleros then quickly assembled a force of ten to twelve thousand men and set out to meet the Rus'. The two armies met near Arcadiopolis (modern Lüleburgaz in Turkish Thrace), some 80 km west of Constantinople. The two primary accounts on the Byzantine side differ on the preliminaries of the battle: Leo the Deacon reports that Skleros sent a scouting detachment ahead under the "patrikios" John Alakaseus, and then gave battle after only a day, but the later chronicle of Skylitzes reports that for a few days, Skleros with his men remained within the walls of Arcadiopolis as the Rus' encamped nearby, and refused to come out and meet them in battle despite their repeated challenges for him to do so. According to Skylitzes, the Rus' quickly became convinced that the imperial army was too afraid to face them; consequently they roamed about the countryside plundering, neglected their camp defences, and spent their nights in heedless revelry.  Skleros eventually set out from the city, and divided his forces into three groups: two divisions were placed in ambush on the wooded sides of the road leading towards the Rus' camp, while another, probably some 2,000–3,000 men, was placed under himself (or Alakaseus in Skylitzes' account) and went forth to attack the Rus' host. The Byzantine detachment quickly came into contact with the Rus' army, and charged the Pecheneg contingent. The Byzantines executed a gradual orderly retreat, turning at intervals to charge back at the pursuing Pechenegs, who had thus become separated from the main body of the Rus' army. This conflict was fierce and bloody, taxing the discipline and endurance of the small Byzantine force. According to Leo the Deacon, at one point one of the Pechenegs charged Bardas himself and delivered a sword blow on his helmet, which was deflected by the metal without doing harm. Bardas' young brother Constantine came to his rescue, killing the Pecheneg.  When the two opposing forces reached the place of the ambush, Bardas ordered the trumpets blown and the two concealed Byzantine divisions attacked the Pechenegs from the flanks and the rear. Cut off from aid and surrounded, the Pechenegs began to panic and flee. One of their leaders tried to rally his men, but he was attacked by Bardas Skleros himself, who killed him with a single sword-blow that reportedly cut him in two from his head down to the waist, through the Pecheneg's helmet and cuirass. The loss of the Pecheneg commander turned the battle into a complete rout, and panic spread to the Bulgarian contingent following behind the Pechenegs, which also suffered heavy casualties in the general chaos. The Byzantine casualties in the battle were low (Skylitzes speaks of 25 dead and Leo of 55) although they lost many horses to the Pecheneg arrows, while the losses of the Rus' force, although certainly lower than Leo's claimed 20,000, were still significant, probably running into several thousands.

Aftermath.

The Byzantines were unable to exploit this victory or pursue the remnants of the Rus' army, since Bardas Phokas rose in revolt in Asia Minor. Bardas Skleros and his men were consequently withdrawn to Asia Minor, whilst Sviatoslav restricted his forces to the north of the Balkan Mountains. In the spring of the next year, however, with Phokas' rebellion subdued, Tzimiskes himself, at the head of his army, advanced north into Bulgaria. The Byzantines took the Bulgarian capital Preslav, capturing the Bulgarian tsar Boris II, and confined the Rus' in the fortress of Dorostolon (modern Silistra). After a three-month siege and a series of pitched battles before the city walls, Sviatoslav conceded defeat and abandoned Bulgaria.  In Hungarian historiography, the Battle of Arcadiopolis is considered as the final chapter of the Hungarian invasions of Europe, a series of plundering raids both westward and southward since the end of the 9th century. Following that the new Grand Prince, Géza consolidated his authority and also supported Christian missionaries from Western Europe (experiencing the fate of the Bulgarian patriarchate after John Tzimiskes's campaign against Bulgaria, when lost its independence), which led to the Christianization of the Magyars and the establishment of the Christian Kingdom of Hungary by the beginning of the new millennium.

The Battle of Arcadiopolis was fought in 970 between a Byzantine army under Bardas Skleros and a Rus' army, the latter also including allied Bulgarian, Pecheneg, and Hungarian (Magyar) contingents. In the preceding years, the Rus' ruler Sviatoslav had conquered Bulgaria, and was now menacing Byzantium as well. The Rus' force had been advancing through Thrace towards Constantinople when it was met by Skleros' force. Having fewer men than the Rus', Skleros prepared an ambush and attacked the Rus' army with a portion of his force. The Byzantines then feigned retreat, and succeeded in drawing off the Pecheneg contingent into the ambush, routing it. The remainder of the Rus' army then suffered heavy casualties from the pursuing Byzantines. The battle was important as it bought time for the Byzantine emperor John I Tzimiskes to settle his internal problems and assemble a large expedition, which eventually defeated Sviatoslav the next year.

Bitva u Arkadiopole se odehrála roku 970 mezi byzantskou armádou vedenou Bardou Sklerem a protibyzantskou koalicí vedenou kyjevským knížetem Svatoslavem I. V době, kdy se odehrála tato bitva, byl na byzantském trůně Jan I. Tzimiskes.


Structure.

Rhabdoviruses have helical symmetry, so their infectious particles are approximately cylindrical in shape. They are characterized by an extremely broad host spectrum ranging from plants to insects and mammals; human-infecting viruses more commonly have icosahedral symmetry and take shapes approximating regular polyhedra.  The rabies genome encodes five proteins: nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G) and polymerase (L). All rhabdoviruses have two major structural components: a helical ribonucleoprotein core (RNP) and a surrounding envelope. In the RNP, genomic RNA is tightly encased by the nucleoprotein. Two other viral proteins, the phosphoprotein and the large protein (L-protein or polymerase) are associated with the RNP. The glycoprotein forms approximately 400 trimeric spikes which are tightly arranged on the surface of the virus. The M protein is associated both with the envelope and the RNP and may be the central protein of rhabdovirus assembly.  "Rabies lyssavirus" has a bullet like shape with a length of about 180 nm and a cross-sectional diameter of about 75 nm. One end is rounded or conical and the other end is planar or concave. The lipoprotein envelope carries knob-like spikes composed of Glycoprotein G. Spikes do not cover the planar end of the virion (virus particle). Beneath the envelope is the membrane or matrix (M) protein layer which may be invaginated at the planar end. The core of the virion consists of helically arranged ribonucleoprotein.

Genome organization.

The rhabdovirus virion is an enveloped, rod- or bullet-shaped structure containing five protein species. The nucleoprotein (N) coats the RNA at the rate of one monomer of protein to nine nucleotides, forming a nucleocapsid with helical symmetry. Associated with the nucleocapsid are copies of P (phosphoprotein) and L (large) protein. The L protein is well named, its gene taking up about half of the genome. Its large size is justified by the fact that it is a multifunctional protein. The M (matrix) protein forms a layer between the nucleocapsid and the envelope, and trimers of G (glycoprotein) form spikes that protrude from the envelope. The genomes of all rhabdoviruses encode these five proteins. Many rhabdoviruses encode one or more proteins in addition to these.

Life cycle.

After receptor binding, "Rabies lyssavirus" enters its host cells through the endosomal transport pathway. Inside the endosome, the low pH value induces the membrane fusion process, thus enabling the viral genome to reach the cytosol. Both processes, receptor binding and membrane fusion, are catalyzed by the glycoprotein G which plays a critical role in pathogenesis (mutant virus without G proteins cannot propagate).  The next step after its entry is the transcription of the viral genome by the P-L polymerase (P is an essential cofactor for the L polymerase) in order to make new viral protein. The viral polymerase can only recognize ribonucleoprotein and cannot use free RNA as template. Transcription is regulated by "cis"-acting sequences on the virus genome and by protein M which is not only essential for virus budding but also regulates the fraction of mRNA production to replication. Later in infection, the activity of the polymerase switches to replication in order to produce full-length positive-strand RNA copies. These complementary RNAs are used as templates to make new negative-strand RNA genomes. They are packaged together with protein N to form ribonucleoprotein which then can form new viruses.

Infection.

In September 1931, Joseph Lennox Pawan of Trinidad found Negri bodies in the brain of a bat with unusual habits. In 1932, Pawan first discovered that infected vampire bats could transmit rabies to humans and other animals.  From the wound of entry, "Rabies lyssavirus" travels quickly along the neural pathways of the peripheral nervous system. The retrograde axonal transport of "Rabies lyssavirus" to the central nervous system (CNS) is the key step of pathogenesis during natural infection. The exact molecular mechanism of this transport is unknown although binding of the P protein from "Rabies lyssavirus" to the dynein light chain protein DYNLL1 has been shown. P also acts as an interferon antagonist, thus decreasing the immune response of the host.  From the CNS, the virus further spreads to other organs. The salivary glands located in the tissues of the mouth and cheeks receive high concentrations of the virus, thus allowing it to be further transmitted due to projectile salivation. Fatality can occur from two days to five years from the time of initial infection. This however depends largely on the species of animal acting as a reservoir. Most infected mammals die within weeks, while strains of a species such as the African yellow mongoose ("Cynictis penicillata") might survive an infection asymptomatically for years.

Signs and symptoms.

The first symptoms of rabies may be very similar to those of the flu including general weakness or discomfort, fever, or headache. These symptoms may last for days. There may be also discomfort or a prickling or itching sensation at the site of bite, progressing within days to symptoms of cerebral dysfunction, anxiety, confusion, agitation. As the disease progresses, the person may experience delirium, abnormal behavior, hallucinations, and insomnia. "Rabies lyssavirus" may also be inactive in its hosts body and become active after a long period of time.

Antigenicity.

Upon viral entry into the body and also after vaccination, the body produces virus neutralizing antibodies which bind and inactivate the virus. Specific regions of the G protein have been shown to be most antigenic in leading to the production of virus neutralizing antibodies. These antigenic sites, or epitopes, are categorized into regions I-IV and minor site a. Previous work has demonstrated that antigenic sites II and III are most commonly targeted by natural neutralizing antibodies. Additionally, a monoclonal antibody with neutralizing functionality has been demonstrated to target antigenic site I. Other proteins, such as the nucleoprotein, have been shown to be unable to elicit production of virus neutralizing antibodies. The epitopes which bind neutralizing antibodies are both linear and conformational.

Evolution.

All extant rabies viruses appear to have evolved within the last 1500 years. There are seven genotypes of "Rabies lyssavirus". In Eurasia cases are due to three of these—genotype 1 (classical rabies) and to a lesser extent genotypes 5 and 6 (European bat lyssaviruses type-1 and -2). Genotype 1 evolved in Europe in the 17th century and spread to Asia, Africa and the Americas as a result of European exploration and colonization.  Bat rabies in North America appears to have been present since 1281 AD (95% confidence interval: 906–1577 AD).  The rabies virus appears to have undergone an evolutionary shift in hosts from Chiroptera (bats) to a species of Carnivora (i.e. raccoon or skunk) as a result of an homologous recombination event that occurred hundreds of years ago This recombination event altered the gene that encodes the virus glycoprotein that is necessary for receptor recognition and binding.

Application.

"Rabies lyssavirus" is used in research for viral neuronal tracing to establish synaptic connections and directionality of synaptic transmission.

Rabies lyssavirus, formerly Rabies virus, is a neurotropic virus that causes rabies in humans and animals. Rabies transmission can occur through the saliva of animals and less commonly through contact with human saliva. "Rabies lyssavirus", like many rhabdoviruses, has an extremely wide host range. In the wild it has been found infecting many mammalian species, while in the laboratory it has been found that birds can be infected, as well as cell cultures from mammals, birds, reptiles and insects.

Virus vztekliny je RNA virus s helikální symetrií a typickým tvarem projektilu. Je původcem vztekliny, akutního, zpravidla smrtelně probíhajícího onemocnění zvířat i člověka.


Habitat.

The wels catfish lives in large, warm lakes and deep, slow-flowing rivers. It prefers to remain in sheltered locations such as holes in the riverbed, sunken trees, etc. It consumes its food in the open water or in the deep, where it can be recognized by its large mouth. Wels catfish are kept in fish ponds as food fish.  An unusual habitat for the species exists inside the Chernobyl exclusion zone, where a small population lives in abandoned cooling ponds and channels at a close distance to the decommissioned power plant. These catfish appear healthy, and are maintaining a position as top predators in the aquatic ecosystem of the immediate area.

Diet.

Like most freshwater bottom feeders, the wels catfish lives on annelid worms, gastropods, insects, crustaceans, and fish. Larger specimens have been observed to also eat frogs, mice, rats, aquatic birds such as ducks and can be cannibalistic. A study published by researchers at the University of Toulouse, France in 2012, documented individuals of this species in an introduced environment lunging out of the water to feed on pigeons on land. Out of the beaching behaviors observed and filmed in this study, 28% were successful in bird capture. Stable isotope analyses of catfish stomach contents using carbon 13 and nitrogen 15 revealed a highly variable dietary composition of terrestrial birds. This is likely the result of adapting their behavior to forage on novel prey in response to new environments upon its introduction to the Tarn River in 1983 since this type of behavior has not been reported within the native range of this species. They can also eat red worms in the fall, but only the river species.

Physical characteristics.

The wels catfish's mouth contains lines of numerous small teeth, two long barbels on the upper jaw and four shorter barbels on the lower jaw. It has a long anal fin that extends to the caudal fin, and a small sharp dorsal fin relatively far forward. The wels relies largely on hearing and smell for hunting prey (owing to its sensitive Weberian apparatus and chemoreceptors respectively), although like many other catfish, the species is characterised with a tapetum lucidum, providing its eyes with a degree of sensitivity at night, when the species is most active. With its sharp pectoral fins, it creates an eddy to disorient its victim, which the predator sucks into its mouth and swallows whole. The skin is very slimy. Skin colour varies with environment. Clear water will give the fish a black color, while muddy water will often tend to produce green-brown specimens. The underside is always pale yellow to white in colour. Albinistic specimens are known to exist and are caught occasionally. Wels swim in a fashion similar to eels, and so can swim backwards.

Size.

With a possible total length up to and a maximum weight of over, the wels catfish is the largest true freshwater fish (as opposed to anadromous or catadromous) in its region (Europe and parts of Asia). However, such lengths are rare and were hard to prove during the last century, but there is a somewhat credible report from the 19th century of a wels catfish of this size. "Brehms Tierleben" cites Heckl's and Kner's old reports from the Danube about specimens long and in weight, and Vogt's 1894 report of a specimen caught in Lake Biel which was long and weighed. In 1856, K. T. Kessler wrote about specimens from the Dnieper River which were over long and weighed up to. (According to the Hungarian naturalist Ottó Hermann [1835-1914], catfish of 300–400 kilograms were also caught in Hungary in the old centuries from the Tisza river.)  Most wels catfish are about long; fish longer than are a rarity. At they can weigh and at they can weigh.  Only under exceptionally good living circumstances can the wels catfish reach lengths of more than, as with the record wels catfish of Kiebingen (near Rottenburg, Germany), which was long and weighed. This giant was surpassed by some even larger specimens from Poland (2,61 m. 109 kg.), the former Soviet states (the Dnieper River in Ukraine, the Volga River in Russia and the Ili River in Kazakhstan), France, Spain (in the Ebro), Italy (in the Po, where a record 2.78m long wels catfish was caught, and Arno), Serbia (in Gruža Lake, where a long specimen weighing was caught on 21 June 2018. and catfish with length of 275cm and weight 117kg at Đerdap gorge on Danube River during the same year ), and Greece, where this fish was released a few decades ago. Greek wels grow well thanks to the mild climate, lack of competition, and good food supply.  Wels have also been observed thriving in the cooling pond of the damaged Chernobyl Nuclear Power Plant. Although believed by tourists to have mutated into large sizes as a result of radioactive fallout, in reality the fish are growing to such proportions due to the absence of humans, hunting and fishing having been outlawed in the exclusion zone following the accident.  The largest accurate weight was for a long specimen from the Po Delta in Italy.  Exceptionally large specimens are rumored to attack humans in rare instances, a claim investigated by extreme angler Jeremy Wade in an episode of the Animal Planet television series "River Monsters" following his capture of three fish, two of about and one of, of which two attempted to attack him following their release. A report in the Austrian newspaper "Der Standard" on 5 August 2009, mentions a wels catfish dragging a fisherman near Győr, Hungary, under water by his right leg after the man attempted to grab the fish in a hold. The man barely escaped with his life from the fish, which must have weighed over, according to him.

Ecology.

There are concerns about the ecological impact of introducing the wels catfish to non-native regions. These concerns take into account the situation in Lake Victoria in Africa, where Nile perch were introduced and rapidly caused the extinction of numerous indigenous species. This severely affected the entire lake, destroying much of the original ecosystem. The introduction of foreign species is almost always a burden on the affected ecosystem. Following the introduction of wels catfish, some fishes' numbers are in clear and rapid decline. Since its introduction in the Mequinenza Reservoir in 1974, it has spread to other parts of the Ebro basin, including its tributaries, especially the Segre River. Some endemic species of Iberian barbels, genus "Barbus" in the Cyprinidae, were once abundant especially in the Ebro river but due to competition from and predation by wels catfish have since disappeared in the middle channel Ebro. The ecology of the river has also changed, as there is now a major growth in aquatic vegetation such as algae. Barbel species from mountain stream tributaries of the Ebro that wels catfish have not colonized are not affected.

Breeding.

The female produces up to 30,000 eggs per kilogram of body weight. The male guards the nest until the brood hatches, which, depending on water temperature, can take from three to ten days. If the water level decreases too much or too fast the male has been observed to splash the eggs with its tail in order to keep them wet.

As a food fish.

Only the flesh of young "Silurus glanis" specimens is valued as food. It is palatable when the catfish weighs less than 15 kg (33 lb). Larger than this size, the fish is highly fatty and not recommended for consumption, but large "S. glanis" are sought out as a sport fish due to their combativeness.

Attacks on people.

Tabloids regularly report attacks caused by various catfish that primarily affected animals (often only the role of the catfish was presumed). In April 2009, an Austrian fisherman was allegedly attacked by an catfish in one of the fishing lakes in Pér, near Győr, Hungary. However, the man reportedly managed to break free.  Similar stories occur in the works of older natural history writers. Alfred Brehm (1829–1884), a German naturalist, published his famous work "The World of Animals" in the 19th century. It was also translated into Hungarian at the beginning of the 20th century. In this, Brehm or the compiling Hungarian scientists write the following:

The wels catfish ( or ; "Silurus glanis"), also called sheatfish, is a species of large catfish native to wide areas of central, southern, and eastern Europe, in the basins of the Baltic, Black, and Caspian Seas. It has been introduced to Western Europe as a prized sport fish and is now found from the United Kingdom east to Kazakhstan and China and south to Greece and Turkey. It is a freshwater fish recognizable by its broad, flat head and wide mouth. Wels catfish can live for at least fifty years.

Sumec velký ("Silurus glanis"; Linné, 1758) z čeledi sumcovitých je vedle jeseterovitých ryb největší sladkovodní rybou v Evropě. Sumec je sportovními rybáři velice vyhledávanou, byť obtížně ulovitelnou rybou, u které je nejmenší lovná míra stanovena zákonem. Je to převážně noční dravec. V poslední době stal předmětem akvakulturního chovu v celé řadě států. Má velký invazní potenciál.