Atlantic walrus (Odobenus rosmarus rosmarus) COSEWIC assessment and status report: chapter 5

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Species Information

• Name and Classification
• Description

Name and Classification

The Atlantic walrus, Odobenus rosmarus rosmarus (Linnaeus, 1758), is a mammal of the Genus Odobenus Brisson, 1762, Family Odobenidae Allen, 1880, Suborder Caniformia (synonym Pinnipedia) and Order Carnivora Bowdich, 1821 (ITIS 2003). It is one of two living subspecies of the walrus, the other being the Pacific walrus (O. r. divergens)^Footnote 1. Common names for the species include walrus (English, Dutch), morse (French), aivik (Inuktitut), hvalros (Danish), mursu (Finnish), rostungur (Icelandic), hvalross (Norwegian), morzh (Russian), morsa (Spanish, Portugese), and valross (Swedish).

Description

The walrus is a large, gregarious marine mammal with front and hind limbs that have developed into flippers (Figure 1). The front flippers can support the animal in an upright position as in the otariids, while the back flippers are structured and function like phocid seal hind flippers. The walrus can be distinguished from other species of marine mammals by its tusks, which are long upper canines, and by its moustache of quill-like whiskers. Adult males are larger than females and have longer, broader tusks (Mansfield 1966; Garlich-Miller and Stewart 1998). Newborn walruses have a coat of silver grey hairs that is soon lost and replaced by a short, sparse coat of brown hair. The sparsely haired skin is cinnamon brown but can appear pink on a warm day, or almost white after a long, cold dive (Bruemmer 1977; Reeves 1995). Adult males have a large muscular neck that is covered by thick, cornified skin. At birth Atlantic walruses are about 120 cm long and weigh about 55 kg (Mansfield 1958); males grow to about 315 cm (~1100 kg) and females to about 277 cm (~800 kg) (Garlich-Miller and Stewart 1998). Pacific walruses grow to a similar length but are heavier on average (MacLaren 1993; Knutsen and Born 1994; Garlich-Miller and Stewart 1998), with longer tusks and a wider skull. Laptev Sea walruses have skull characteristics similar to those of the Pacific walrus and are intermediate in size between the Atlantic and Pacific subspecies.

Detailed reviews are available for the walrus (e.g. Fay 1985) and for its Atlantic (Reeves 1978; Born et al. 1995; Stewart 2002) and Pacific subspecies (e.g. Fay 1982), as is a bibliography up to January 1993 (Stewart 1993).

Figure 1: Drawing of an Adult Male Atlantic Walrus (Odobenus rosmarus rosmarus)

Artist Gerald Kuehl; © Canada Department of Fisheries and Oceans, reproduced with permission.