Odobenus Rosmarus

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Marine Ecology
Blog 1
By: Elizabeth Hargis & Shannon Ashworth
Odobenus Rosmarus
Image result for pacific walrus
Introduction:
The Odobenus Rosmarus, more commonly known as the walrus, is a marine mammal belonging to the genus Odobenus and is further divided into three subspecies. This large marine mammal can be found within the waters of the arctic ocean (O. r. rosmarus), the pacific ocean (O. r. divergens), or the laptev sea of the arctic ocean (O. r. laptevi).
Anatomy

 The anatomy of a walrus is very interesting in that it allows them to be both land and marine animals. As in most species there is a difference between the anatomy of male and female walruses. Male walruses are significantly heavier than female walruses in body weight. And although both males and females have tusks, the male tusks are wider and longer than those on the females. Tusks can grow up to three feet in length and can weigh up to twelve pounds. The Pacific walrus has been observed to have longer tusks than those found in the Atlantic. The tusks provide a multifaceted purpose for the walrus. They can determine hierarchy in the pack by length and strength. The walrus with the longest tusks will become the most dominant and will therefore get the best spots to rest and most opportunities to mate with females. Although the tusks are a unique aspect of the walrus, the most unique aspect of their anatomy is their vibrissae. Walruses do not have good vision due to the small morphology of their eyes. Therefore, the walruses utilize the vibrissae to scavenge for food and identify when dangers are present. The vibrissae are the structures that appear as whiskers on the walrus and are numerous. There can be up to 400-700 vibrissae on the face of the walrus that are all individually attached to muscles, have their own blood supply, and contain a network of nerves. Once the vibrissae signal to the walrus that there is a food source nearby or danger in the proximity the motility of the walrus comes from its hind and fore flippers. Other organisms often use their flippers to assist them in navigation while swimming, however, walruses mainly utilize their flippers while on land and use the entirety of their body while swimming. The exterior anatomy of the walrus is very unique to its genus and is especially suitable for survival in their environment.
 
Habitat
Image result for odobenus rosmarus location mapA majority of walruses live in areas with relatively low air temperatures and prefer areas with large patches of ice where they can relocate periodically to birth their young.  The walrus can be found anywhere that the water is frigid ranging from the arctic ocean to the North pole. The air temperature in these ranges can be anywhere from -15 TO 5 degrees Celsius. The food that a walrus relies on for survival are a variety of molluscs, being able of consuming four-thousand clams in one feeding. Although the walrus prefers molluscs they tend to be opportunistic feeders and have been known to feed on a wide variety of other bottom feeders that are available . As aforementioned the walrus is both a land and marine mammal that spends approximately two-thirds of its life in the water. Although the walrus spends a vast majority of its life in the water it can only hold its breath for thirty minutes and dives to depths between eighty to ninety meters.   The purpose of the walruses deep dives are to acquire shellfish and other organisms to sustain their hunger.
Behavior
Walruses are a group of very social animals. Due to necessity and desire, they live in packs and remain in close proximity to each other during all times on land. The closeness of the group is needed to help the walruses trap body heat since their only mechanism of defense against the cold is their blubber. Amongst the pack there will be social rankings present and apparent due to the migrating of the walruses to one group or another. For example, a walrus would migrate to the group of non-mature males, mature males, mature females ready to mate, or females who have become mothers depending on their role. One of the most unique behavioral practices of walruses is their communication. The walruses have an acute sense of hearing and can recognize a call from another walrus a mile away. They use multiple sounds to communicate amongst each other such as whistles, barks, or loud bellows. Walruses are a very nurturing species. Mothers are very attached to their calfs and will even mother an orphaned baby if the situation arises. Despite the seeming division amongst the pack, without each group, the would not thrive in their habitats.
 
Role in the Marine Ecosystem
The walrus is classified as a pinniped meaning that it is a fin-footed, semi aquatic marine mammal. One of the roles pinnipeds play in the marine ecosystem is through their biological background. These marine mammals were most likely once mainly an aquatic organism and have since adapted features allowing them to inhabit both terrestrial and aquatic habitats. The significance of the adaptations of the pinnipeds are that not only did this allow them to escape potential predators but it also paved the way for many organisms that we see today. Pinnipeds, in this case particularly walruses, can contribute to the change in community structure within their ecosystem. When a walrus is searching for food it often contributes to the turnover of nutrients as well meaning that whenever a walrus is eating or searching for food it brings other nutrients along with it.
Conclusion
In conclusion the walrus is a semi aquatic mammal living on both land and in the water. This is allowed due to adaptations that have enabled the walrus to escape the threat of predators. The walrus affects the marine ecosystem in its evolution as well as its turnover of nutrients within the sea. The walrus is a complex organism that has unique anatomical, social, and behavioral characteristics. Overall the walrus is a diverse animal that is not only influenced by many factors but it also influences the world around it.

(walrus_range.jpg)
Bradford, Alina. “Walrus Facts.” LiveScience, Purch, 21 Nov. 2014, www.livescience.com/27442-walrus-facts.html.
Entertainment, SeaWorld Parks &. “Walrus.” Animals: Explore. Discover. Connect., seaworld.org/Animal-Info/Animal-Bytes/Mammals/Walrus.
“Walrus Anatomy.” Animal Facts and Information, www.bioexpedition.com/walrus-anatomy/.
“Walrus Behavior.” Animal Facts and Information, www.bioexpedition.com/walrus-behavior/.
“Walrus Feeding.” Walrus Facts and Information, Walrus world, 22 Nov. 2013,

Wartzok, Douglas. “Physiology of behaviour in pinnipeds.” The Behaviour of Pinnipeds, 1991, pp. 236–299., doi:10.1007/978-94-011-3100-1_5

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