Ribbon Seal
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| Phoca fasciata (Zimmermann, 1783) |
The Ribbon Seal (Phoca fasciata) is a seal from the family Phocidae. It can be found in arctic regions.
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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.
Ribbon seals have 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. Ribbon seals can grow about 1.6 m (5 ft) long, weighing 95 kg (209 lbs) in both genders.
[edit] Habitat
Ribbon seals live in the arctic parts of the Pacific Ocean. During winter and spring, they haul out on pack ice to breed, molt, and give birth. During this time, they are found at the ice front in the Bering and Okhotsk Seas.[1]. 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 their habits during this time, as they are so far from land and human observation. Ribbon seals almost never come to land.
[edit] Behaviour
Their diet consists almost exclusively of pelagic creatures: fish like pollock, eelpout arctic cod and cephalopods such as squid or octopus; young seals eat crustacean as well. Ribbon seals dive to depths of up to 200m in search of food. Ribbon seals are solitary and form 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.[2] 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 killer whale, Greenland shark and 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.
[edit] References
- Seal Specialist Group (1996). Histriophoca fasciata. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
