This video was filmed during December 2014 in the Sea World, San Diego, California, USA.
Review: Abdel Rahman El Gamal (Founder of the video channel)
Eating habits and food preferences
Walruses have a diverse diet and feed on many marine organisms such as shrimp, crabs, sea cucumbers, various mollusks and other benthic invertebrates (e.g. worms, gastropods, cephalopods). However, clams are their preferred food as an adult walrus may eat as many as 3,000 to 6,000 clams in a single feeding session. In general, pregnant females increase food consumption about 30% to 40%.
The foraging of walruses on the benthic communities the along the sea floor, they use jets of water and with the help of the active flipper movements; they clear the burrowing invertebrates such as clams. The disturbance of sea bottom will help release the trapped nutrients into the water column and hence encouraging the richness of benthos organisms. The uniquely curved palate as well as the powerful lips of walruses enables them to rapidly withdraw and suck their prey. When the normal food for walruses turns scarce, they are known to eat carcasses of young seals.
Predation
Due to its great size and tusks, the walrus has only two natural predators: the killer whale(orca) and the polar bear. The “Polar bear–walrus” and “Killer whale-walrus” battles are often difficult and may involve injuries and undetermined outcomes. However, both predators are most likely to prey on walrus calves.
Reproduction
Most male walruses are sexually mature at about eight to ten years, but do not typically mate until 15 years when he is fully developed and becomes able to compete for females. Most females are sexually mature at about five to six years. However, successful reproduction begins at about ten years.
The breeding begins when herds of non-pregnant, estrous females meet male herds and move to the mating place which is –in case of the Pacific- would be the central and south Bering Sea.
Ice-bound group of estrous females is aggregated by nearby in-water adult males, which may perform competitive vocal displays including bell-like sounds, under water clicks, teeth clacking and whistles at the water surface. Females leave the ice to join displaying males where mating takes place underwater and remote from shore. Bulls either maintain a reasonable distance of about 7 to 10 m or fight violently with each other.
Total gestation is 15 to 16 months including 3-4 months as free-floating in the uterus before implanting itself on the uterine wall and continued to develop. The delayed implantation –which is common among pinnipeds- is a biological mechanism to ensure that the calf will be born when environmental conditions are optimal for its survival. A female generally gives birth to a single calf at a time, though twins have been recorded.
Calves are usually born on the ice. Newborn calves weigh about 45 to 75 kg and are about 95 to 123 cm long. By one month of age calves turn to strong swimmers.
Female mothers and calves tend to gather in “nursery herds” separate from the bulls and other females. Most calves nurse for about two years before weaning. Nursing usually takes place in the water, but calves sometimes nurse while the mother-calf pair is hauled out on ice or land. Mother’s milk is occasionally supplemented with a small amount of solid food as early as six months of age. Males grow slightly faster than females. During nursing, a female mother defends and protects her calf and may shelter it under her chest between her foreflippers. Young female calves usually remain with their mother’s herd while young males may stay for additional two or three years before joining an all-male herd.
Utilization by man
The walrus has played an important role in the cultures of many indigenous Arctic peoples. Walruses have been hunted and killed for their meat, blubber, skin, tusks (ivory), and bones.
The meat, is often preserved and used as an important winter nutrition source; the flippers are fermented and stored as a delicacy until spring; tusks and bones were historically used for tools, as well as material for handicrafts; the oil was rendered for warmth and light; the tough skin have been used to make ropes and boat coverings.
In the light of the technological development some of the traditional uses of walrus are no longer important. However, walrus meat remains an important part of local diets. Similarly, the tusk carving and engraving continue to be an important art form.
Sources: Defenders of Wildlife, National Geographic, Sea World, Wikipedia
