| Steller's sea cow | |
|---|---|
| Drawing from circa mid 18th century | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Sirenia |
| Family: | Dugongidae |
| Subfamily: | †Hydrodamalinae Palmer, 1895 |
| Genus: | †Hydrodamalis Retzius, 1794 |
| Species: | †H. gigas |
| Binomial name | |
| Hydrodamalis gigas (Zimmermann, 1780) |
|
Steller's sea cow (Hydrodamalis gigas) was a large herbivorous marine mammal. In historical times, it was the largest member of the order Sirenia, which includes its closest living relative, the dugong (Dugong dugon), and the manatees (Trichechus spp.). Formerly abundant throughout the North Pacific, its range was limited to a single, isolated population surrounding the uninhabited Commander Islands by 1741 when it was first described by Georg Wilhelm Steller, chief naturalist on an expedition led by explorer Vitus Bering.[2] Within 27 years of discovery by Europeans, the slow-moving and easily-captured Steller's sea cow was hunted to extinction.
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The sea cow grew to at least 8 meters (26 ft) to 9 meters (30 ft) in length as an adult,[3] much larger than the manatee or dugong; however, concerning their weight, Steller's work contains two contradictory estimates: 4 and 24.3 metric tons. The true value is estimated to lie between these figures, at around 8 to 10 t.[4] It looked somewhat like a large seal, but had two stout forelimbs and a whale-like fluke. According to Steller, "The animal never comes out on shore, but always lives in the water. Its skin is black and thick, like the bark of an old oak…, its head in proportion to the body is small…, it has no teeth, but only two flat white bones—one above, the other below". It was completely tame, according to Steller. They fed on a variety of kelp. Wherever sea cows had been feeding, heaps of stalks and roots of kelp were washed ashore. The sea cow was also a slow swimmer and apparently was unable to submerge.[5]
The population of sea cows was small and limited in range when Steller first described them. Steller said they were numerous and found in herds, but zoologist Leonhard Hess Stejneger later estimated that at discovery there had been fewer than 1,500 remaining, and thus had been in immediate danger of extinction from overhunting by humans.[6] They were quickly wiped out by the sailors, seal hunters, and fur traders that followed Bering's route past the islands to Alaska, who hunted them both for food and for their skins, which were used to make boats. They were also hunted for their valuable subcutaneous fat, which was not only used for food (usually as a butter substitute), but also for oil lamps because it did not give off any smoke or odor and could be kept for a long time in warm weather without spoiling. By 1768, 27 years after it had been discovered by Europeans, Steller's sea cow was extinct.
Fossils indicate that Steller's sea cow was formerly widespread along the North Pacific coast, reaching south to Japan and California. Given the rapidity with which its last population was eliminated, it is likely that aboriginal hunting caused its extinction over the rest of its original range (aboriginal peoples apparently never inhabited the Commander Islands).[7]
It has been argued that the sea cow's decline may have also been an indirect response to the harvest of sea otters by aboriginal people from the inland areas. With the otters reduced, the population of sea urchins would have increased and reduced availability of kelp, the sea cow's primary source of food. Thus, aboriginal hunting of both species may have contributed to the sea cow's disappearance from continental shorelines.[7] However, in historic times aboriginal hunting had depleted sea otter populations only in localized areas.[7] The sea cow would have been easy prey for aboriginal hunters, who would likely have exterminated accessible populations with or without simultaneous otter hunting. In any event, the sea cow was limited to coastal areas off islands without a human population by the time Bering arrived, and was already endangered.[8]
Sea cows appear in Rudyard Kipling's short story "The White Seal", where they show the title character a place of refuge from human hunters.
In Jules Verne's 1870 novel Twenty Thousand Leagues Under the Sea, the travelers in Captain Nemo's fictional submarine Nautilus encounter various sirenians during their journey. On February 10 they encounter a female dugong in the Red Sea; Nemo states that hunting has made sirenians scarce, yet Ned Land harpoons the animal to eat. It is described as over 7 m long with a mass of 5000 kg, which are far in excess of what a dugong would measure and weigh, though they would be appropriate for Steller's sea cow, which was to be found in colder northern waters, although it had already been extinct for a century by then. On April 12, observing a group of West Indian manatees off Dutch Guiana, Professor Arronax extols their ecological value. Thus, a concern for environmental themes was expressed in Verne's writing.
In contemporary literature, the Steller's sea cow appears in a book of poetry, Species Evanescens, by Russian poet Andrei Bronnikov. In this book, the poet compares the fate of the extinct animal with the fate of its discoverer. The book examines the personality of Georg Steller and depicts the Kamchatka expedition during which the discovery of the Steller's sea cow was made.