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| SCIENTIFIC
CLASSIFICATION |
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| COMMON
NAME: |
walrus |
| KINGDOM: |
Animalia |
| PHYLUM: |
Chordata |
| CLASS: |
Mammalia |
| ORDER: |
Pinnipedia |
| FAMILY: |
Odobenidae |
| GENUS
SPECIES: |
Odobenus
rosmarus |
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| DESCRIPTION: |
Walruses
are very distinctive having a large, robust, fusiform
body that is usually reddish-brown in color. On
their head region, walruses lack external ear flaps,
have hundreds of short, vibrissae (whiskers), and
both males and females possess large tusks. Like
other pinnipeds, the fore and hind limbs of a walrus
are modified into flippers. Although hair is present
on the rest of the body, it is absent on the flippers.
The foreflippers are short and square in shape with
tiny claws on all digits, and the hind flippers
are triangular in shape with larger claws on the
three middle digits. On land, walruses are capable
of rotating their hind flippers under their pelvic
girdle to walk on all fours in a similar manner
to sea lions. |
| MALE |
Adult
males are slightly larger than females with longer
and stouter tusks. |
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| SIZE: |
The
Pacific subspecies is larger than the Atlantic.
Newborn calves are about 95-123 cm (3-4 ft.) long. |
| MALE |
2.7-3.6
m (9-12 ft.) |
| FEMALE |
2.3-3.1
m (7.5 to 10 ft.) |
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| WEIGHT: |
Newborn
claves weigh about 45-75 kg (99-156 lb.) |
| MALE |
About
800-1,700 kg ((1,764-3,748 lb.) |
| FEMALE |
About
400-1,250 kg (882-2,756 lb.) |
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| DIET: |
Mainly
bivalve mollusks such as clams; also other benthic
invertebrates such as marine worms, snails, sea
cucumbers, squids, and crabs. May occasionally prey
upon fish such as polar cod and scavenge on seal
carcasses. There are rare cases of very large, male
walruses that habitually prey upon seals, especially
ringed and bearded seals. |
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| GESTATION: |
15-16
months, including a period of delayed implantation |
| ESTRAL
PERIOD |
December
through March |
| NURSING
DURATION |
2
or more years (wean) |
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| SEXUAL
MATURITY: |
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| MALE |
8-10
years; successful reproduction probably not until
about 15 years |
| FEMALE |
5-6
years; successful reproduction at about 10 years |
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| RANGE: |
Arctic
Sea - both Pacific and Atlantic (Bering, Laptev
and Chukchi seas) |
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| HABITAT: |
In
relatively shallow water - generally not more than
80 m (262 ft.) deep. Hauls out on ice floes, pack
ice and small rocky islands when ice is not present.
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| POPULATION: |
GLOBAL |
About
250,000 |
| REGIONAL |
Pacific
walrus population about 200,000 |
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| STATUS: |
IUCN |
Not
listed |
| CITES |
Appendix
III |
| USFWS |
Not
listed |
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| 1. |
Walruses
spend about two-thirds of their lives in the water.
Highly social in nature, huge herds of walruses
haul out (leave the water to get on land) on sea
ice to rest and bear their young. Most walruses
live where the air temperature is about -15°
to 5°C (5° to 41°F). |
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| 2. |
A thick layer of blubber insulates the walrus. Blubber
may be up to 15 cm (6 in.) thick. During the winter,
blubber may account for one-third of a walrus's
total body mass. Blubber also streamlines the body
and functions as an excess energy reserve. |
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| 3. |
To locate food, walruses use their vibrissae (whiskers).
A walrus has about 400-700 vibrissae on its snout.
Vibrissae are attached to muscles and are supplied
with blood and nerves. A walrus moves its snout
through bottom sediment to find food. Abrasion patterns
of the tusks show that they are dragged through
the sediment, but are not used to dig up prey. Walruses
may also take in mouthfuls of water and squirt powerful
jets at the sea floor, excavating burrowing invertebrates
such as clams and may consume 3,000-6,000 clams
within a single feeding. |
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| 4. |
The
primary functions of the walruses' prominent tusks
seem to be aiding in hauling out on ice and rocky
shores and in establishing social dominance. |
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| 5. |
For
more information about walrus, explore the walrus
info book. |
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| As
for other marine mammals, the U.S. Marine Mammal
Protection Act of 1972 protects walrus populations. |
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|
|
Byrum,
J. Pinnipeds From Pole to Pole: Seals, Sea
Lions and Walruses. SeaWorld Education Department
Publication. San Diego. SeaWorld, Inc. 2000.
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|
Jefferson, T.J. Leatherwood, S. and M.A. Webber.
FAO Species Identification Guide. Marine Mammals
of the World. Rome. FAO, 1993. |
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|
Nowak, Ronald M. (ed.). Walker's Mammals of
the World. Vol. II. Baltimore: Johns Hopkins
University Press, 1991.
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| Parker,
S. (ed.). Grizmek's Encyclopedia of Mammals.
Vol. IV. New York: McGraw-Hill Publishing Co.,
1990. |
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| Reeves,
R. R., Stewart, B.S., Clapman, P.J., and J.A. Powell
(Peter Folkens illustrator). National Audubon
Society: Guide to Marine Mammals of the World.
New York: Random House, 2002. |
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| Reeves,
R.R., Stewart, B.S. and S. Stephen. The Sierra
Club Handbook of Seals and Sirenians. San Francisco:
Sierra Club Books, 1992. |
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| Riedman,
M. The Pinnipeds: Seals, Sea Lions and Walruses.
Berkeley and Los Angeles. University of California
Press. 1990. |
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| http://animaldiversity.ummz.umich.edu |
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