WALRUS Common Name: walrus Class: Mammalia Order: Pinnipedia Family: Odobenidae Genus species: Odobenus rosmarus Weight: Male walruses weigh about 800-1,700 kg (1,764-3,748 lb.). Females weigh about 400-1,250 kg (882-2,756 lb.). Atlantic walruses are slightly smaller than Pacific walruses. Social behavior: Herds of walruses haul out (leave the water to get on land) on sea ice to rest and bear their young. They prefer snow-covered moving pack ice or ice floes, but will also haul out on small rocky islands when ice isn't present. Diet: Walruses prefer to eat bivalve mollusks such as clams. They also eat many other kinds of invertebrates including worms, snails, squids, and crabs. Fun Facts 1. Walruses spend about two-thirds of their lives in the water. 2. Most walruses live where the air temperature is about -15 to +5 degree C (5-41 degree F). 3. 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' total body mass. Blubber also streamlines the body and functions as an excess energy reserve. 4. To locate food, walruses use their vibrissae (whiskers). A walrus has about 400 to 700 vibrissae in 13 to 15 rows 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. Total world population of walruses is about 250,000 animals. Two walrus subspecies exist--Pacific and Atlantic. Both live in the Arctic.
informations Walruses are members of a widely distributed group of marine animals known as pinnipeds (pinna, a wing or fin; and pedis, a foot), a group which also includes the seals and sea lions. Walruses are the largest pinnipeds in arctic and subarctic seas. They are most commonly found in relatively shallow water areas, close to ice or land. Their geographic range completely encircles the Polar Basin. Two forms are presently recognized: the Pacific walrus (Odobenus rosmarus divergens) and the Atlantic walrus (Odobenus rosmarus rosmarus). The principal differences between the two are in the longer tusks and larger body size of the Pacific walrus. The groups may be regarded as closely related but geographically separated subspecies. Today there are far more Pacific than Atlantic walruses. The 1990 population of the Pacific subspecies was estimated at about 201,000 animals. They are the mainstay of several Eskimo villages. Their flesh is used for food and the skins as boat coverings. The intestines were traditionally used to make rain gear. In the American sector of the Bering and Chukchi seas, walruses occur seasonally from Bristol Bay to Point Barrow. Most of the animals undertake a northward spring migration and return south during the fall. These movements are directly related to the seasonal advance and retreat of the sea ice. About 12,000 to 16,000 bulls remain in the Bristol Bay area from March through October. These males migrate northward in the fall to the St. Lawrence Island area, where they join the rest of the herd to spend the winter and spring in the ice pack. General description: The genus name for the walrus, Odobenus (meaning tooth-walker), refers to one of their most prominent characteristics, their tusks. These tusks, which are elongated upper canine teeth, are present in both males and females. The body form is basically like a sea lion, and they have flexible hind flippers that can be rotated forward, a thick, heavy neck, and a broad muzzle that bears a heavy, bristly moustache. They are huge animals. Adult bulls often approach 2 tons in weight, and the females may exceed 1 ton. Adult bulls can be recognized by their larger size, broad muzzle, heavy tusks, and the presence of numerous large bumps on the neck and shoulders. Life history: Walrus calves are born mostly in late April or early May during the spring migration. They weigh 100 to 160 pounds (45-73 kg) at birth. Calves are dependent upon their mothers for at least 18 months and occasionally for as long as 2 1/2 years. Most females do not begin to breed until 6 or 7 years of age. Mating occurs during January and February, but growth of the fetus does not begin until about mid-June. This delay in fetal growth is thought to occur in all pinnipeds. The total gestation period, from conception to birth, is about 15 months. However, the actual period of fetal growth is about 11 months. Most cows do not breed again until the year following the birth of their last calf. Thus, calves are produced in alternate years by females in their prime. Calves are produced less frequently by the older females. By 2 years of age, the young weigh about 750 pounds (341 kg). When the females are 11 or 12 years old, they weigh approximately 2,000 pounds (909 kg), their maximum weight. The males continue growing until at least 14 to 16 years of age. The age of an individual walrus (except for very old animals) can be determined by the number of rings or "annual layers" observed in cross-sections of the teeth. In the older animals, some of the rings laid down during the first few years of life are worn away. However, examination of teeth has shown that walruses can reach the age of 40 years. Due to rather constant, significant, and selective hunting pressure, as well as other factors, it is doubtful that very many walruses die of old age. Food habits: Walruses feed mainly on bottom-dwelling invertebrates found on the relatively shallow and rich Bering-Chukchi Platform. Major food items include several different kinds of clams. Only the fleshy parts are eaten. It is believed that these parts are torn away from the rest of the clam by strong suction, a method of feeding for which the mouth of the walrus is ideally designed. The mouth of a walrus is narrow, with an unusually high roof, strong thick lips which are not deeply cleft along the side of the face (the gape is extremely limited), and a thick piston-like tongue. The tusks are probably not used to any great extent during feeding. The rejected shells can be found on the sea floor alongside the holes and furrows made by feeding animals. Other food items include snails, crabs, shrimps, worms, and occasionally seals. Walruses usually find food by brushing the sea-bottom with their broad, flat muzzles. Behavior: The tusks are used for fighting, for climbing on both land and ice, and for emergencies of various kinds. A female walrus was observed literally demolishing a heavy piece of ice to free her calf, which had fallen into a crevasse. The tusks were as effective as a pick-axe. The presence of 12 men within 30 feet did not distract her from her task. Attempts to assist her in her efforts were met by furious charges and a threatening noise made by rapidly opening and closing her mouth. The noise sounded much like someone banging a pipe with a hammer. In due time she freed her calf and swam off, carrying it on her back. Cows will not abandon their calves, and vice versa. The cows make every effort to rescue their offspring. They often carry their dead calves away from the hunters. Walruses, especially young males, will push dead and badly wounded animals (often larger than themselves) off an ice floe, out of the reach of the hunters. They will frequently return to an ice floe for as long as wounded animals continue to bellow. This sometimes places both people and boats in jeopardy. The return is not a reprisal attack but an attempt to lead the wounded animals to safety. A person imitating the sounds of a walrus can frequently get them to return. Walruses (with the exception of some young bulls) are usually not malicious, but their inquisitiveness, size, and great strength demand caution of those who approach them. Tusks are used a great deal in mutual display, with the strongest animals (usually with the largest tusks) being dominant over the others. When animals on an ice floe are disturbed, which happens frequently, they will raise their heads high, prominently showing their tusks. Animals with smaller tusks will usually move away or become respectfully quiet. The only serious battles (and these are quite brutal) are between animals of the same body and tusk size. Hunting: Walrus hunting is conducted from all of the Eskimo villages near which the animals occur. However, the bulk of the annual harvest is taken from the villages in and near Bering Strait, mainly Gambell, Savoonga, Nome/King Island, and Little Diomede Island. Hunting loss can be high. Several thousand animals are killed annually in Alaska. Some walruses are also taken by Siberian Eskimos and by Russian commercial hunting vessels. The most favorable period for hunting walrus is during the spring and summer when the animals are passing the villages on their way north. Hunting is good on St. Lawrence Island during May, and progressively later at the most northerly locations. Walruses reach the vicinity of Wainwright and Barrow during late July or early August.
pacific walrus Scientific Name: Odobenus rosmarus Home: Alaskan and Chukchi Sea, Bristol Bay, and the Bering Sea Description: Up to 14 feet long and weighing 2000 pounds. Reddish- skinned sea mammal with three foot ivory tusks. Short neck with bristly mustache, flippers. The walrus has the best creature mustache! With as many as 700 hairs packed on their snout, a walrus has a nose for sniffing out food and nuzzle-kissing their friends! They love to sunbathe, and in the cold waters they swim in -- sometimes diving as deep as 300 feet -- a little sun must be nice and warm! Usually timid and shy, but easily provoked, the walrus has two massive tusks which it uses in three ways: to get girls, to get a grip when climbing out of the water onto ice, and to anchor themselves on the ocean bottom while digging for clams. The biggest tusked bull has breeding rights. The walrus dines on clams, snails, mussels, and 40 other kinds of invertebrates all found at the bottom of the sea. Walruses communicate to each other with knocks, bells, clacks, and whistles, and love to hang out in big piles on the beach of more than 100! ##The walrus has air sacs under their throats that they can fill like floatation bubbles and bob vertically in the water and sleep! ##A walrus can move on land as fast as a man can run! Unlike seals, who have to drag their hind ends around, a walrus can walk on all fours! ##The walrus has a special strategy to dig for clams -- the SQUIRT! A walrus squirts high-power jets of water out of their mouths! They use this talent like a water drill to get to clams under the mud! =========================================================================
Habitat and Distribution A. Distribution Walruses are circumpolar, but they are concentrated in several geographically separated areas, with little or no chance of interbreeding. 1. Pacific walruses inhabit the Bering, Chukchi, and Laptev seas. 2. Atlantic walruses inhabit coastal areas of north eastern Canada and Greenland. B. Habitat. 1. Walruses are generally found where the water is not more than about 80 m (262 ft.) deep. They prefer a habitat with a gravelly bottom. 2. Walruses spend about two-thirds of their lives in the water. 3. Walruses haul out to rest and bear their young. a. Walruses are adapted to a habitat of sea ice and prefer snow-covered moving pack ice or ice floes to land. They haul out on small rocky islands when ice is not present. b. Eskimos call a traditional walrus haul-out area an ooglit. 4. Walruses are not generally found where heavy, snow-covered ice covers more than 80% of the sea's surface. 5. Most walruses live where the air temperature is about -15 to +5 degree C (5 to 41 degree F). C. Migration. 1. The walruses' migration follows the extent of the pack ice. Throughout the year, they occur primarily in or near the southern periphery of the pack ice. a. Pacific walruses winter in the central and south Bering Sea and summer in the Chukchi Sea. b. Migration of the Canadian population is less well-known. They seem to remain in the same general vicinity all year. 2. Walruses migrate primarily by swimming, but they may also ride ice floes. 3. Some walruses may migrate more than 3,000 km (1,863 mi.) each year. 4. Pacific walrus adult females and young walruses are more migratory than adult males. a. Pacific walrus calves are born on the northward migration to the Chukchi Sea. b. Several thousand Pacific walrus bulls remain in the south Bering Sea during the summer. When the ice melts, these bulls haul out on islands. c. Some researchers have suggested that the hormones that control sperm development may also inhibit migration in adult males. D. Population. 1. Total world walrus population is about 250,000 animals. 2. Pacific walrus population is more than 200,000 animals. a. The Pacific walrus population has been hunted to depletion and allowed to recover several times. b. After the latest population depletion, which began in the 1930s, Pacific walruses were given protection by Russia, the State of Alaska, and the U.S. federal government. This protection led to the eventual recovery of the Pacific walrus population (more than 200,000 animals). Walruses reoccupied areas where they had not been seen for several years. c. By the early 1980s, walruses appeared leaner, they increased their consumption of alternate foods such as fishes, natural mortality increased, and birth rates decreased. This evidence supports the theory that the Pacific walrus population may have approached the carrying capacity of its environment. As the Pacific walrus population has grown, annual subsistence catches by indigenous Arctic peoples has increased. Some scientists predict that, without adequate long-term management, natural and human-related mortality factors will rapidly reduce the population once more. If you want morinformation contact us Dr.HOOMAN
Physical Characteristics 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. 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
Adaptations for an Aquatic Environment A. Swimming. 1. Normal swimming speed for walruses is about 7 kph (4.3 mph). They are capable of short bursts of up to 35 kph (21.7 mph). 2. Most propulsion comes from alternate strokes of the hind flippers. Foreflippers also work with the hind flippers for maneuvering. B. Diving. 1. Walruses generally breathe at the surface for about one minute after every five to eight minutes of subsurface activity. Walruses can remain submerged for as long as ten minutes. 2. A walrus' benthic prey usually inhabits waters no more than about 80 m (263 ft.) deep; a walrus generally dives no deeper than this. Deeper dives, however, have been documented. When the stomach contents of one individual were examined, researchers concluded that the walrus dove at least 91 m (299 ft.). Another observation confirmed a dive of 113 m (371 ft.) and a submersion time of 25 minutes. 3. All marine mammals have special physiological adaptations for diving. These adaptations enable a walrus to conserve oxygen while it is below water. a. Walruses, like other mammals, slow their heartbeat while diving. b. When diving, blood is shunted away from tissues tolerant of low oxygen levels toward organs where oxygen is needed, such as the heart and brain. c. The muscle of walruses has a high content of the oxygen-binding protein myoglobin. Myoglobin transports and stores oxygen in muscle tissue. 4. Pharyngeal muscles prevent water from entering the trachea when the walrus opens its mouth below water. C. Respiration. A walrus breathes through its nostrils and through its mouth. D. Thermoregulation. 1. Heat loss in water is 27 times faster than in air at the same temperature. 2. A walrus' core body temperature is about 36.6 degree C (97.9 degree F). There is a heat gradient throughout the blubber to the skin. A walrus' skin stays about 1 to 3 degree C (1.8 to 5.4 degree F) warmer than the water. 3. From about -20 to +15 degree C (-4 to +59 degree F) a walrus' metabolism doesn't change, and the temperature doesn't appear to affect the walrus' behavior. 4. Walruses can withstand even cooler temperatures; they have been observed at -35 degree C (-31 degree F). 5. In cold water, blood is shunted inward as blood vessels in the skin constrict, reducing heat loss to the environment. The skin appears pale, almost white. 6. When warm, blood vessels in the skin dilate (expand), losing heat to the environment. The skin appears pink. 7. When air temperatures rise above about 15 degree C (59 degree F), walruses often stay in the water to stay cool. 8. Walruses deposit most of their body fat into a thick layer of blubber that lies just underneath the skin. This blubber layer insulates the walrus and streamlines its body. It also functions as an energy reserve. Blubber may be up to 10 cm (3.9 in.) thick. During the winter, blubber may account for one third of a walrus' total body mass 9. Walruses seek out physical contact with other walruses. This helps walruses retain their body heat rather than lose it to the external environment. Physical contact is also indicative of their gregarious nature
Walruses Communication A. Sound Production. 1. Walruses have vocal cords. 2. Walruses produce sounds both above and below water. 3. Walruses are among the most vocal of the pinnipeds. They produce growls, grunts, barks, soft whistles, rasps, and clicks. 4. Male walruses produce bell-like sounds below water. These sounds are not produced by the vocal cords but originate from air sacs, which extend from the pharynx. 5. Calves bellow if disturbed. 6. Adults engaged in dominance conflicts may snort, cough, or roar. B. Display Behavior. 1. Walruses communicate through auditory and visual displays. 2. During courtship, males display visually and vocally from the water. Stereotyped sequences of sounds occur both above and below water. Below-water sounds include clicks or knocks, bell-like sounds, and taps. Above-water sounds include teeth-clacking and whistles. 3. Males engage in tusk-threat displays to establish dominance. C. Other Communication. 1. Walruses communicate through sound, sight, touch, and smell. 2. Tactual communication occurs through body contact. a. Walruses haul out in herds in close contact with one another. b. A mother shelters her calf under her chest between her foreflippers. A calf often rides on its mother's back in the water. c. Adults engaged in dominance conflicts may strike each other with their tusks. d. Courtship displays continue until a female physically contacts a displaying male in the water.