Ribbon Seal
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| Histriophoca fasciata (Zimmermann, 1783) |
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 Ribbon seal range (blue - summer, pink - maximal)
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The Ribbon Seal (Histriophoca fasciata) is a pinniped from the true seal family (Phocidae). A seasonally ice-bound species, it is found in the Arctic and Subarctic regions of the North Pacific Ocean, notably in the Bering Sea and Sea of Okhotsk. It is the only species in the genus Histriophoca.[1]
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[edit] Physical description
Adult seals are recognizable by their black skin, which carries four white markings: a strip around the neck, one around the tail and a circular marking on each body side, which encloses the front fins. The contrast is particularly strong with the males, while with females the difference in colour between bright and dark portions is often less conspicuous. Newborn Ribbon Seal pups have white natal fur. After moulting their natal fur, their colour changes to blue-grey on their backs and silvery beneath; after some years some portions become darker and others brighter, and only at the age of four years does the typical design show.
The Ribbon Seal has a large inflatable air sac that is connected to the trachea and extends on the right side over the ribs. It is larger in males than in females, and it is thought that it is used to produce underwater vocalizations, perhaps for attracting a mate. The Ribbon Seal can grow about 1.6 m (5 ft) long, weighing 95 kg (209 lb) in both genders.
[edit] Habitat
The Ribbon Seal lives in the Arctic parts of the Pacific Ocean. During winter and spring, it hauls out on pack ice to breed, molt, and give birth. During this time, it is found at the ice front in the Bering and Okhotsk Seas.[3] During the summer and autumn, the Ribbon Seal lives in open water, though some move north as the ice recedes with warmer temperatures. Little is known about its habit during this time, as it is so far from land and human observation. The Ribbon Seal almost never comes to land.
[edit] Behaviour
Its diet consists almost exclusively of pelagic creatures: fish like pollocks, eelpouts, the Arctic Cod and cephalopods such as squid and octopus; young seals eat crustaceans as well. The Ribbon Seal dives to depths of up to 200 m in search of food. The Ribbon Seal is solitary and forms no herds. Female Ribbon Seals reach sexual maturity at 2 to 5 years and males reach sexual maturity at 3 to 6 years, and an individual may reach twenty to twenty-five years of age. Mating takes place from late April to early May.[3] Young animals are born on the ice in April and May. They are fed for four weeks on their mother's milk, then leave their mother. They remain on the ice for a few more weeks, in which they lose their dense white fur and lose a drastic amount of weight. After this period, they are able to dive and hunt by themselves.
Predators of the Ribbon Seal include the Orca, the Greenland Shark and the Polar Bear.
[edit] Protection
Young Ribbon Seals look like young Harp Seals, and like these, they were hunted for their fur. Since they do not form herds, Ribbon Seals were more difficult to catch than Harp Seals. Since the Soviet Union limited the hunt on Ribbon Seals in 1969, their population has recovered. The current population is around 250,000.
In March 2008 the US government agreed to study Alaska's Ribbon Seal population and is considering adding it to the endangered species list. This is likely a direct result of warming of the oceans which is decreasing the winter ice flows.[citation needed]
[edit] References
- ^ a b Wozencraft, W. C. (16 November 2005). in Wilson, D. E., and Reeder, D. M. (eds): Mammal Species of the World, 3rd edition, Johns Hopkins University Press. ISBN 0-801-88221-4.
- ^ Seal Specialist Group (1996). Histriophoca fasciata. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
- ^ a b SCS: Ribbon Seal (Phoca fasciata)
[edit] External links
- Overview pages on ribbon seals (Histriophoca fasciata) hosted by:
- Range map on OBIS*SEAMAP
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