Steller's sea cow

|alt=The skull has a hole on the snout and large eye sockets on either side and flattens out on the top; no teeth are visible. Steller's sea cows are reported to have grown to long as adults, much larger than extant sirenians. In 1987, a rather complete skeleton was found on Bering Island measuring . In 2017, another such skeleton was found on Bering Island measuring , and in life probably about . Georg Steller's writings contain two contradictory estimates of weight: . The true value is estimated to fall between these figures, at about . This size made the sea cow one of the largest mammals of the Holocene epoch, along with baleen whales and some few toothed whales, Its skin was brownish-black, with white patches on some individuals. It was smooth along its back and rough on its sides, with crater-like depressions most likely caused by parasites. This rough texture led to the animal being nicknamed the "bark animal". Hair on its body was sparse, but the insides of the sea cow's flippers were covered in bristles. According to Steller, these plates (or "masticatory pads") were held together by interdental papillae, a part of the gums, and had many small holes containing nerves and arteries. The sea cow's spine is believed to have had seven cervical (neck), 17 thoracic, three lumbar, and 34 caudal (tail) vertebrae. Its ribs were large, with five of 17 pairs making contact with the sternum; it had no clavicles. In all collected skeletons of the sea cow, the manus is missing; since Dusisiren—the sister taxon of Hydrodamalis—had reduced phalanges (finger bones), Steller's sea cow possibly did not have a manus at all. The only specimen with preserved bones from the wrist down is a specimen under study found in Komae, Tokyo, Japan, which preserve a fragment of metacarpal bone. The sea cow's heart was in weight; its stomach measured long and wide. The full length of its intestinal tract was about , equaling more than 20 times the animal's length. The sea cow had no gallbladder, but did have a wide common bile duct. Its anus was in width, with its feces resembling those of horses. The male's penis was long. ==Ecology and behavior==

, mid-1800s|alt=Two large, oval-shaped plates haveh a ridge running down the middle, and grooves run diagonally from either side of the ridge. Many bristles of varying sizes and widths occur, but all are stiff at the base and taper out at the end. The several small rectangular teeth have numerous holes in them. Whether Steller's sea cow had any natural predators is unknown. It may have been hunted by killer whales and sharks, though its buoyancy may have made it difficult for killer whales to drown, and the rocky kelp forests in which the sea cow lived may have deterred sharks. According to Steller, the adults guarded the young from predators. It was first formally described as Sirenocyamus rhytinae in 1846 by Johann Friedrich von Brandt, although it has since been placed into the genus Cyamus as Cyamus rhytinae. It was the only species of cyamid amphipod to be reported inhabiting a sirenian. Steller also identified an endoparasite in the sea cows, which was likely an ascarid nematode. ==Taxonomy==

Phylogeny Steller's sea cow was a member of the genus Hydrodamalis, a group of large sirenians, whose sister taxon was Dusisiren. Like those of Steller's sea cow, the ancestors of Dusisiren lived in tropical mangroves before adapting to the cold climates of the North Pacific. Hydrodamalis and Dusisiren are classified together in the subfamily Hydrodamalinae, which diverged from other sirenians around 4 to 8 mya. Steller's sea cow is a member of the family Dugongidae, the sole surviving member of which, and thus Steller's sea cow's closest living relative is the dugong (Dugong dugon). Steller's sea cow was a direct descendant of the Cuesta sea cow (H. cuestae), The Takikawa sea cow (H. spissa) of Japan is thought of by some researchers to be a taxonomic synonym of the Cuesta sea cow, but based on a comparison of endocasts, the Takikawa and Steller's sea cows are more derived than the Cuesta sea cow. This has led some to believe that the Takikawa sea cow is its own species. the animals on the island included relict populations of sea cows, sea otters, Steller sea lions, and northern fur seals. As the crew hunted the animals to survive, Steller described them in detail. Steller's account was included in his posthumous publication De bestiis marinis, or The Beasts of the Sea, which was published in 1751 by the Russian Academy of Sciences in Saint Petersburg. Zoologist Eberhard von Zimmermann formally described Steller's sea cow in 1780 as Manati gigas. Biologist Anders Jahan Retzius in 1794 put the sea cow in the new genus Hydrodamalis, with the specific name of stelleri, in honor of Steller. It is known that Adolf Erik Nordenskiöld, Benedykt Dybowski, and Leonhard Hess Stejneger unearthed many skeletal remains from different individuals in the late 1800s, from which composite skeletons were assembled. As of 2006, 27 nearly complete skeletons and 62 complete skulls have been found, but most of them are assemblages of bones from two to 16 different individuals. Illustrations The Pallas Picture is the only known drawing of Steller's sea cow believed to be from a complete specimen. It was published by Peter Simon Pallas in his 1840 work . Pallas did not specify a source; Stejneger suggested it may have been one of the original illustrations produced by Friedrich Plenisner, a member of Vitus Bering's crew as a painter and surveyor who drew a figure of a female sea cow on Steller's request. Most of Plenisner's depictions were lost during transit from Siberia to Saint Petersburg. ==Range==

The range of Steller's sea cow at the time of its discovery was apparently restricted to the shallow seas around the Commander Islands, which include Bering and Copper Islands. The first fossils discovered outside the Commander Islands were found in interglacial Pleistocene deposits in Amchitka, The southernmost find is a Middle Pleistocene rib bone from the Bōsō Peninsula of Japan. The remains of three individuals were found preserved in the South Bight Formation of Amchitka; as late Pleistocene interglacial deposits are rare in the Aleutians, the discovery suggests that sea cows were abundant during that era. According to Steller, the sea cow often resided in the shallow, sandy shorelines and in the mouths of freshwater rivers. possibly with viable populations that were in contact with humans in the western Aleutian Islands prior to Steller's discovery in 1741. A sea cow rib discovered in 1998 on Kiska Island was dated to around 1,000 years old, and is now in the possession of the Burke Museum in Seattle; the dating may be skewed due to the marine reservoir effect, which causes radiocarbon-dated marine specimens to appear several hundred years older than they are (marine reservoir effect is caused by the large reserves of C14 in the ocean, and it is more likely that the animal died between 1710 and 1785). A 2004 study reported that sea cow bones discovered on Adak Island were around 1,700 years old, and sea cow bones discovered on Buldir Island were found to be around 1,600 years old. It is possible that these bones were from cetaceans and were misclassified. ==Interactions with humans==

Extinction Genetic evidence suggests the Steller's sea cows around the Commander Islands were the last of a much more ubiquitous population dispersed across the North Pacific coastal zones. They had the same genetic diversity as the last and rather inbred population of woolly mammoths on Wrangel Island. During glacial periods and reduction in sea levels and temperatures, suitable habitat substantially regressed, fragmenting the population. By the time sea levels stabilized around 5,000 years ago, the population had already plummeted. Together, these indicate that even without human influence, the Steller's sea cow would have still been a dead clade walking, with the vast majority of the population having already gone extinct from natural climatic and sea level shifts, with the tiny remaining population at major risk from a genetic extinction vortex. When Europeans discovered them, there may have been only 2,000 individuals left. It was also hunted to collect its valuable subcutaneous fat. The animal was hunted and used by Ivan Krassilnikov in 1754 and Ivan Korovin 1762, but Dimitri Bragin, in 1772, and others later, did not see it. Brandt thus concluded that by 1768, twenty-seven years after it had been discovered by Europeans, the species was extinct. In 1887, Stejneger estimated that there had been fewer than 1,500 individuals remaining at the time of Steller's discovery, and argued there was already an immediate danger of the sea cow's extinction. may be due to lost ecosystem functions associated with the Steller's sea cow. This indicates that due to the sea cow's extinction, the ecosystem dynamics and resilience of North Pacific kelp forests may have already been compromised well before more well-known modern stressors like overharvesting and climate change. in the Gulf of Anadyr. The crew reported seeing six of these animals ranging from , with trunks and split lips. There have also been alleged sightings by local fishermen in the northern Kuril Islands, and around the Kamchatka and Chukchi peninsulas. Uses in 1948, Zoologisk Museum Steller's sea cow was described as being "tasty" by Steller; the meat was said to have a taste similar to corned beef, though it was tougher, redder, and needed to be cooked longer. The meat was abundant on the animal, and slow to spoil, perhaps due to the high amount of salt in the animal's diet effectively curing it. The fat could be used for cooking and as an odorless lamp oil. The crew of the St. Peter drank the fat in cups and Steller described it as having a taste like almond oil. The thick, sweet milk of female sea cows could be drunk or made into butter, The ethnographer Elizabeth Porfirevna Orlova, from the Russian Museum of Ethnography, was working on the Commander Island Aleuts from August to September 1961. Her research includes notes about a game of accuracy, called kakan ("stones") played with the bones of the Steller's sea cow. Kakan was usually played at home between adults during bad weather, at least during Orlova's fieldwork. In literature, media, and folklore talking to sea cows in Rudyard Kipling's The Jungle Book (1895)|alt=On slightly yellow paper using black ink, there is Kotick the white seal with his arms protruding straight up out of the water. He is facing a sea cow who is darkly shaded, has large nostrils, small eyes, stocky body, and covered in seaweed. Behind Kotick is another sea cow who is eating seaweed, and in the background there are many other sea cows. One of the sea cows is sticking its tail out of the water, which resembles that of a dolphin. The coastline is visible to the right. In the story The White Seal from The Jungle Book by Rudyard Kipling, which takes place in the Bering Sea, Kotick the rare white seal consults Sea Cow during his journey to find a new home. Tales of a Sea Cow is a 2012 docufiction film by Icelandic-French artist Etienne de France about a fictional 2006 discovery of Steller's sea cows off the coast of Greenland. The film has been exhibited in art museums and universities in Europe. Steller's sea cows appear in two books of poetry: Nach der Natur (1995) by Winfried Georg Sebald, and Species Evanescens (2009) by Russian poet Andrei Bronnikov. Bronnikov's book depicts the events of the Great Northern Expedition through the eyes of Steller; Sebald's book looks at the conflict between man and nature, including the extinction of Steller's sea cow. The 2023 novel Beasts of the Sea (Elolliset) by Finnish author and literary scholar Iida Turpeinen uses Steller's sea cow and its demise as a central theme. It features multiple characters at different times in history that were involved with the animal, beginning from Steller's expedition and telling how the complete skeleton was conserved and ended up in the Helsinki Museum of Natural History. Scottish poet John Glenday published the poem "The Kelp Eaters" in his 2003 volume, Grain, describing the beauty and loving nature of the sea cows and their harpooning by the narrator and his companions. The poem carries the epigraph "From "Journal of a Voyage with Bering 1741-1742" By Georg Wilhelm Steller". Genetic research and potential revival In 2021, the nuclear genome of the species was sequenced from skeletal remains. Ben Lamm of Colossal Biosciences has also stated that he and his company want to revive the species after they complete their first four projects (woolly mammoth, dodo, thylacine, and northern white rhinoceros) and have an artificial animal womb developed. ==See also==