The Steller's sea cow is an extinct herbivorous marine mammal. It was the
largest member of the order Sirenia, which includes its closest living
relative, the dugong, and the manatees. It reached up to 9 metres in length,
making it among the largest mammals other than whales to have existed in the
holocene epoch. Although the sea cow had formerly been abundant throughout the
North Pacific, by 1741, when it was first described by Georg Wilhelm
Steller, chief naturalist on an expedition led by explorer Vitus Bering,
its range had been limited to a single, isolated population surrounding the
uninhabited Commander Islands. Within 27 years of discovery by Europeans, the
slow-moving and easily captured Steller's sea cow was hunted to
extinction. Description
The sea cow grew to at least 8 to 9 m in length as an adult, 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. It looked somewhat like a
large seal, but had two stout forelimbs and a whale-like fluke.
According to Steller, it "is not the sea cow of Aristotle, for it never comes
upon dry land to feed", but it can use its fore limbs for a number of tasks:
swimming, walking on the shallows of the shore, supporting himself on the rocks,
digging for algae and seagrasses, fighting, and embracing each other.
"It is covered with a thick hide, more like unto the bark of an ancient oak
than unto the skin of an animal; the manatee’s hide is black, mangy,
wrinkled, rough, hard, and tough; it is void of hairs, and almost impervious to
an ax or to the point of a hook." Its head is small and short compared to
the huge body. The upper lip is so large, so broad, and extends so far
beyond the mandible, that the mouth appears to be located underneath the
skull. The mouth is rather small, toothless, and equipped with double
lips, both above and below. When it closes its mouth, the space between the
lips is filled up with a dense array of very thick white bristles, 1.5 in long.
These bristles take the place of teeth and are used to pull out seaweed and
hold food. Mastication is performed by two white bones or solid tooth masses.
Behavior It was completely tame, according to
Steller. It 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.
Habitat The number of sea cows was small and
limited in range when Steller first described them; although he had said
they were numerous and found in herds, 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. There is
evidence that sea cows also inhabited the Near Islands during historic times.
Oral tradition on Attu stated that sea cows were still hunted there after their
extinction on the Commander Islands. Fossils indicate Steller's sea cow was
formerly widespread along the North Pacific coast, reaching south to Japan
and California in the US. Given the rapidity with which its last population
was eliminated, aboriginal hunting likely caused its extinction over the
rest of its original range. Population and extinction
The species was quickly wiped out by the sailors, seal hunters, and fur traders
who followed Bering's route past the islands to Alaska, who hunted it both
for food and for skins, which were used to make boats. It was also hunted for
its valuable subcutaneous fat, which was not only used for food, but also for oil
lamps because it did not give off any smoke or odour 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.
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. In historic times, though,
aboriginal hunting had depleted sea otter populations only in localized
areas. 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. It has been demonstrated that the extinction of the sea cow could
have been effected solely by the hunting of the sea cow for meat by fur-trading
mariners of the time, and no other factors needed to have contributed.
Portrayals in media Tales of a Sea Cow is a 2012 film by
Icelandic-French artist Etienne de France "documenting" a fictional 2006
re-discovery by scientists of a population of Steller's sea cows off the
coast of Greenland via sound recordings or their calls. This film has been
exhibited in public institutions such as art museums and universities in Europe.
Art critic Annick Buread found the film a " tongue in cheek and joyous but
unsettling fable". See also
List of extinct animals List of extinct animals of North America
Evolution of sirenians References
External links Animal Diversity Web
Steller's sea cow information from the AMIQ Institute
Hans Rothauscher's Die Stellersche Seekuh site
Illustration of a sea cow skeleton and an extract from Steller's description