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Physical Characteristics
Walruses are characterized by their large size, and by their
tusks and numerous vibrissae. The Pacific walrus is slightly larger than the Atlantic
walrus.
A. Size.
1. Male Pacific walruses weigh about 800 to 1,700 kg (1,764-3,748 lb.) and are about 2.7 to 3.6 m (9-12 ft.) long.
2. Female Pacific walruses weigh about 400 to 1,250 kg (882-2,756 lb.) and are about 2.3 to 3.1 m (7.5-10 ft.) long.
3. Atlantic walruses are slightly smaller: males weigh about 908 kg (2,000 lb.) and reach lengths of 2.9 m (9.5 ft.). Females weigh about 794 kg (1,750 lb.) and reach lengths of 2.4 m (8 ft.).
4. The northern and southern elephant seals are the only pinnipeds that, full-grown,
can be larger than the walrus.
B. Body shape.
A walrus has a rounded, fusiform body.
C. Coloration.
1. Generally, walruses are cinnamon-brown overall.
2. Walruses appear quite pale in the water; after a sustained period in very cold water, they may appear almost white. They are pink in warm weather when tiny blood vessels in the skin dilate and circulation increases. This increased skin circulation sheds excess body heat.
3. Calves at birth are ashen gray to brown. Within a week or two, calves become
tawny-brown. The coloration pales with age. In general, younger individuals are darkest.
D. Flippers.
1. Limbs are modified into flippers.
2. Flippers are hairless. The skin on the soles of a walrus' flippers is thick and rough, providing traction on land and ice.
3. The foreflippers, or pectoral flippers, have all the major skeletal elements of the forelimbs of land mammals, but they're foreshortened and modified.
a. A walrus' foreflippers are short and square. Each foreflipper has five digits of about equal length. Each digit has a small and inconspicuous claw.
b. While swimming, a walrus holds its foreflippers against its body or uses them for steering.
c. On land, a walrus positions its foreflippers at right angles to the body for walking.
4. Walruses have triangular-shaped hind flippers. Hind flippers have five bony digits. Claws on the three middle digits are larger than those on the outer two digits.
a. Walruses use alternating strokes of the hind flippers to propel themselves in water.
b. Like sea lions, walruses can rotate their hind flippers under their pelvic girdle, enabling them to walk on all fours.
E. Head.
1. A walrus' head is square and broad, with conspicuous tusks and whiskers.
2. A walrus has about 400 to 700
vibrissae (whiskers) in 13 to 15 rows on its snout. Vibrissae are attached to muscles and are supplied with blood and nerves.3. Most walruses have 18 teeth.
A walrus' upper canine teeth are modified into long ivory tusks.a. Both males and females have tusks. The tusks of males tend to be longer, straighter, and stouter than those of females.
b. Tusks erupt during a calf's first summer or fall.
c. Abrasion wears enamel from the crown.
d. The primary functions of the tusks are establishing social dominance and hauling out onto ice or rocky shores.
e. Tusks can grow to a length of 100 cm (39 in.) in males and 80 cm (31.5 in.) in
females. Tusks grow for about 15 years, although they may continue to grow in males.
4. Eyes are small and located high and toward the sides of the head.
5. Ears, located just behind the eyes, are small inconspicuous openings with no external ear flaps.
6. Paired nostrils are located on the snout above the vibrissae. Nostrils are closed in
the resting state.
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E. Tail.
Walruses do not have a distinct tail.
F. Skin and Hair.
1. A walrus' skin is thick and tough. It may reach a thickness of 2 to 4 cm (0.79-1.6 in.). It is thickest on the neck and shoulders of adult males, where it protects the animal against jabs by the tusks of other walruses.
2. The skin of males often has large nodules; these are absent in females. Since the nodules appear at the time of puberty, they are presumed by some researchers to be a secondary sex characteristic.
3. Hair is about 7 to 12 mm (0.3 to 0.5 in.) long over most of the body. It is shortest on the face and absent on the flippers.
4. Hair is densest on juveniles and becomes less dense with age.
5. Molting a. An annual molt (hair-shedding) for most males takes place from June to
August. Females may molt over a more prolonged period. Molting in walruses is gradual;
individual hairs fall out and are replaced. b. Calves shed a fine prenatal coat, called the lanugo,
about two to three months before they are born. They shed a natal coat at about one to two
months of age.
