Why does a walrus have a layer of fat

Nursing mothers, for instance, build up thick stores of blubber before giving birth. Blubber insulates walruses from the cold. Their blood vessel constrict or get smaller in cold water. Last but not least, not only does blubber keep walruses warm, but makes their hide much tougher for predators, like polar bears, to penetrate.

They have a protective hide! What do walruses eat? They have an opportunistic diet, feeding on not only mollusks, clams, shrimp, sea cucumbers and mussels, but also on other pinnipeds. Seal tissue has been observed in fairly significant portions of walrus stomachs in the Pacific However, they prefer clams that they forage for at the sea bottom using their ultra sensitive vibrissae or whiskers. When they dive, they clear the murky sea bottom with jets of water and active flipper movements while using their whiskers to feel for clams.

Then the walrus sucks the meat out of the clam by sealing its powerful lips to the shell and withdrawing its piston-like tongue rapidly into its mouth creating a powerful vacuum. The mouth of the walrus, or its palate, is uniquely designed to enable effective and powerful suction.

The bulls can be very dangerous especially around mating time and the cow can be aggressive when she has a young calf. They are most known to attack people in boats and can cause serious harm with their tusks or by capsizing a boat or kayak. There is one documented case in Spitzbergen Svalbard where walruses capsized a boat killing all aboard. The plural for walrus is walruses, and the collective nouns for a group of walruses are herd, huddle or pod.

Pods of walruses come out of the water to congregate on land. Walruses haul-out onto land primarily for birthing, nursing and resting meanwhile they use sea ice as haul-out sites to avoid predators. While on land, it is not uncommon for a walrus to sleep for an uninterrupted 19 sold hours. Walruses can stay away for almost 4 days while at sea and then they need sleep. Sea ice haul-outs are more commonly used for shorter and more frequent haul-outs.

Hauling-out is important to walruses because it allows for thermoregulation, therefore wind, temperature and time of day are factors on haul-out locations and duration of time out of the water. But the desperate need for haul-outs is dangerous for walruses. Walruses spend most of their time on sea ice. They migrate with moving ice floes and need ice in order to rest between dives for food. But climate change is dramatically shrinking available sea ice for walruses.

As a result, thousands of walruses are swimming much farther distances to seek refuge on shore when no ice is available. With declining ice, commutes to shore can be more than miles. Blubber is a thick layer of fat , also called adipose tissue, directly under the skin of all marine mammal s. Blubber covers the entire body of animals such as seals, whales, and walruses—except for their fins, flippers, and flukes. Blubber an important part of a marine mammal's anatomy.

It store s energy, insulates heat, and increases buoyancy. Energy is stored in the thick, oily layer of blubber. The energy stored in blubber includes both protein s mostly collagen and fats mostly lipid s. The ability of blubber to use these stored nutrient s means marine mammals are not forced to search for food for long periods of time. Nursing mother s, for instance, build up thick stores of blubber before giving birth. In addition to feeding offspring , mothers cannot regularly search for food.

They rely on the energy stored in their blubber. Blubber also insulate s marine mammals, or helps keep them warm in icy waters. This insulation is necessary. Mammal s are warm-blooded, meaning their body temperature stays about the same no matter what the temperature outside is.

Keeping a warm body temperature in cold water requires more energy than keeping a warm body temperature in warm water. Some marine mammals, such as sea otters, have a thick fur coat, as well as blubber, to insulate them. To insulate the marine mammal, blood vessel s in blubber constrict , or get smaller, in cold water. Constricted blood vessels reduce the flow of blood, thus reducing the energy required to heat the body.

This conserve s heat. Finally, blubber helps marine mammals stay buoyant, or float. Blubber is generally less dense than the ocean water surrounding it, so animals naturally float. Animals with the thickest blubber, such as right whales, are found in Arctic and Antarctic regions. The walrus is a large, flippered marine mammal which has a thick layer of fat, called blubber, under its skin to keep it warm.

Males can grow to an enormous size, with some growing to a weight of over kilograms. The walrus has a muscular body which it uses to manoeuvre through the water. Its four flippers help with steering and it is also able to turn its rear flippers forwards in order to help it move on land. The inner layer contained slightly higher amounts of saturated FAs and slightly lower amounts of shorter-chained monounsaturated FAs than the outer layer, which is consistent with the directional differences of these FA groups with blubber depth observed in 18 adult male Atlantic walruses Skoglund et al.

Our study suggests that sampling the outer layer may sufficiently represent percent lipid content of the full blubber depth at any of the three body sites. Although very low to substantial stratification of fatty acids with blubber depth have been shown to occur among pinnipeds Lambert et al.

FA composition at the sternum of lactating walruses in our study Figure 6 is similar to FA levels found in adult female Pacific walruses sampled in by Budge et al. FA profiles were characterized by high levels of monounsaturated FAs, primarily n-7, followed by n-9 and n Polyunsaturated FAs were dominated by n-3, n-3, and n-3, and saturated FAs were dominated by These patterns were also evident in full-depth FA profiles of Atlantic walruses opportunistically sampled in summer at two locations in the Canadian Arctic Thiemann et al.

In contrast, Quakenbush et al. Similarly, although Noren et al. Rather, body condition was highly correlated to total blubber mass estimated from three measures of blubber thickness at seven girth sites, data that cannot be collected in most field settings. Thus, percent lipid collected at a single body site may be a more sensitive indicator of total body fat than a measure of blubber thickness. The walruses in our study were harvested by subsistence hunters in spring as the population migrates from its winter range in the Bering Sea to its summering grounds in the Chukchi Sea Fay, Sea ice habitat in these seas, particularly in the Chukchi Sea, are undergoing rapid change in seasonal ice extent and thickness due to climate warming.

The summer of marked the start of record-setting low summertime sea ice extents over the Chukchi Sea shelf Stroeve et al. This reduction in ice extent caused walruses to begin hauling out in large numbers on the coasts of Alaska and northern Chukotka for extended periods in autumn Jay et al.

Decline in sea ice conditions are expected to continue through this century Wang et al. Investigating body indices that correlate with fat stores may be useful in this endeavor if they can be shown to relate to environmental conditions, human-caused stressors, or population vital rates Stevenson and Woods, ; Booth et al. Measures of lipid content in walrus blubber samples may be worth further exploration as an index of body condition.

The datasets analyzed for this study can be found in the U. CJ, SI, and AF contributed to conception and design of the study and wrote sections of the manuscript. SI organized the database. CJ performed the statistical analysis and wrote the first draft of the manuscript. All authors contributed to manuscript revision, read, and approved the submitted version.

This research was funded by the U. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Snyder and B. Benter for blubber sample collections. We also thank the Eskimo Walrus Commission for their interest in supporting this project. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U. American Society of Mammalogists Standard measurements of seals. Booth, C. Methods for monitoring for the population consequences of disturbance in marine mammals: a review. Bromaghin, J. Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data.

Budge, S. Studying trophic ecology in marine ecosystems using fatty acids: a primer on analysis and interpretation. Fatty acid biomarkers reveal niche separation in an Arctic benthic food web. Castrillon, J. The blubber adipocyte index: a nondestructive biomarker of adiposity in humpback whales Megaptera novaeangliae. Farmer, N. Population consequences of disturbance by offshore oil and gas activity for endangered sperm whales Physeter macrocephalus. Fay, F. Number 74, U. Department of the Interior, Fish and Wildlife Service.

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