What do walruses feed on

There are two main subspecies of walrus The Atlantic and Pacific — which both occupy different areas of the Arctic. Anatoly Kochnev.

They weigh a tonne Male Pacific walruses can reach 3. Both male and female walruses have large tusks They use these tusks to help them haul themselves out of the water and onto sea ice. They can live to around 40 years old And it shows. Walruses are rarely found in deep water They seem to prefer feeding at the bottom of shallow waters, eating clams, molluscs, worms, snails, soft shell crabs, shrimp and sea cucumbers. Pacific walruses spend spring and summer feeding over a huge continental shelf They feed on the shallow continental shelf in the Chukchi Sea.

Sophie Lanfear. Atlantic walruses prefer to rest ashore Unlike Pacific walruses, Atlantic walruses prefer to rest ashore, as most feeding grounds in the Atlantic are closer to land. Walruses are highly susceptible to disturbance and noise During their mass gatherings, stampedes can occur as easily spooked walruses attempt to reach the water.

The greatest threat to walruses is climate change Melting sea ice means more Pacific walruses are resting on land, further from their feeding grounds. In this way, comparison between all four behaviours was possible. Behavioural category "right flipper wave" was pooled with "left flipper wave" and "water-jetting" with "muzzle use" to meet the conditions for this test.

A Friedmann's test [ 32 ] was used to test for consistent differences in the time spent on each behaviour across recordings. To test whether the right and left flippers were used in a ratio different from , a Binomial test two-tailed [ 32 ] was carried out for each recording Table 2.

The test was done on the numbers of the different recording angels for each of the four behaviours. The sample consisted of 6 adult and 17 juvenile specimens of both sexes, originating from Greenland O. The semi-quantitative assessment of whether a skeleton was that of an adult or a juvenile was taken from the written data protocol made by the Zoological Museums curators with one consideration being closed or open epiphyses.

The following measurements were made where possible to the nearest mm on right and left bones Figure 6 from each specimen using callipers:.

The bones of the forelimb of a walrus Odobenus rosmarus showing measurements used in the study of lateralized limb use. Photo by Anders Galatius. I: The four measured bones are marked. II: Measurements of the scapula. A: Length, B: Height. III: Measurements of the humerus. A: Epiphyses unattached, B: Epiphyses attached. IV: Measurements of the radius. A: Epiphyses attached, B: Epiphyses unattached. V: Measurement of ulna, epiphyses unattached. All measurements were made by the same observer.

To test for variance differences between subspecies, age and sex an F-test [ 32 ] was used. Since the data were not normally distributed, a Wilcoxon non-parametric signed rank test [ 32 ] was used to test for differences in bone length and mass. If epiphyses were attached to both right and left bones, these were included in the measurements.

Lengths were not measured if any damage to the bone that might influence the length, was evident. The right and left scapula, humerus, radius and ulna were also weighed to the nearest gram on a digital balance. Masses were not measured if an epiphysis was only attached to one bone of a pair, or if any damage to the bone that might influence the mass was evident.

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Journal of Zoology. Altmann J: Observational study of behavior: Sampling Methods. Download references. We thank Dr. Ron A. Forchhammer for valuable comments and improvements to previous versions of the manuscript. The assistance and support of the following institutes and people are acknowledged: The Danish Polar Centre and the military sledge-patrol Sirius for help with logistics, NERI, Silkeborg for technical support, Mogens Andersen for providing access to the collection of the Zoological Museum of Copenhagen and Mads C.

Walruses Diet by Types. The most notable feature of walruses is their pair of tusks. In the real sense, these are their canine teeth, which can grow to about 1.

These tusks play an instrumental role during navigation, and they also offer protective armor when faced with predators. Compared to female walruses, males are larger. Walruses can grow to a weight of about 2 tons. Female walruses weigh over kg. Walruses have round heads, and their muzzles are lined with thick vibrissae. These Arctic giants do not have external ears.

They have thick skin, which is underlined by very thick blubber, whose thickness can be 15 cm. Walruses are excellent swimmers and divers.

They can dive to depths of about 90 m to forage. These organisms are very social among each other. They can form herds of about 2, members. How Do Walruses Hunt? This eating behavior can be translated to about kg per day for a male walrus weighing kg.

Adult walruses use their magnificent tusks as weapons to ward off predators. Walrus calves tend to be more vulnerable to predators. Examples of organisms that prey on walruses include polar bears and killer whales. In bivalve mollusks, the clams are probably the favorite diet of these mammals, consuming about 3, to 6, clams during one feeding. Each dive lasts for about 5 to 20 minutes and the walrus consumes about 60 clams in one dive. They often forage for clams in muddy waters of the sea floor by spotting the prey through their acute vibrissae due to poor visibility.

In order to clear the murky waters and locate invertebrates like clams, walruses are found to squirt jets of water at the sea floor. They are found to swallow the clam whole by sucking off its siphon. The walrus will dive to the sea bottom to eat clams and bivalve mollusks. Walruses usually suck the meat out of the marine organisms and they use their piston-like tongue to do so. Scientists however do not know how much do and why do walruses eat seals.

They have the ability to prey on pound-bearded seal.