Желдеңіз иті (Histriophoca fasciata) сипаттамасы

Species of mammal

The ribbon seal (Histriophoca fasciata) is a medium sized 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 distinguished by its striking coloration, with two wide white strips and two white circles against dark brown or black fur. It is the only living species in the genus Histriophoca,

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 color between bright and dark portions is often less conspicuous. Newborn ribbon seal pups have white natal fur. After moulting their natal fur, their color changes to blue grey on their backs and silvery beneath. Over the course of three years, portions of the fur become darker and others brighter after every molt, and only at the age of four years does the striped pattern emerge. Like other phocids, it possesses enlarged auditory bullae and lacks a sagittal crest. The ribbon seal can grow to a length of about and a weight of , with males being larger than females. The main predators of ribbon seals include great white sharks and orcas.

Male ribbon seals are typically larger than females. This is particularly recognizable in their skull morphology because male nares openings are much larger than female nares openings.

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. During the winter and spring, the ribbon seal lives in open water, though some move south 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 always comes to land. Thus far, there have been three acknowledged instances where ribbon seals have been found as far south as Squamish, British Columbia, Long Beach, Washington, and even further south at Morro Bay, California. There was nothing to suggest that illness was the cause of the seals appearance, as they appeared to be healthy.

Ribbon seals are rarely seen out on the ice and snow. Their method of movement on the ice is highly specialized. While quickly undulating their body in serpentine motion, they grip into the ice with their claws and use alternating flipper strokes to pull themselves across the ice's surface. It has been observed that this form of locomotion is rendered ineffective on other surfaces, most likely due to the increased friction between the animal's fur and the substrate. Adult seals have relatively weak and smooth canines because their food does not need to be viciously torn.

Ribbon seals have a polygynous mating system, where males mate with multiple females. Ribbon seals mate and give birth on pack ice rookeries, sea ice that is not connected to land. Males use vocalizations to defend breeding territories or to attract mates. Males become sexually mature at three to six years old, females become sexually mature between two and five years old. Breeding occurs once annually, and takes place usually in late May to June, corresponding to the loss of sea ice in spring. Pregnant females have a gestation of approximately ten to eleven months, Instead, it became a U. S. National Marine Fisheries Service Species of Concern. The US Government's National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NMFS), has some concerns regarding status and threats of some species, for which insufficient information is available to list them under the US Endangered Species Act. In the summer of 2009 the Center for Biological Diversity filed suit to get the decision changed. On July 10, 2013, after again reviewing the status of this species, the National Marine Fisheries Service found that listing under the ESA was not warranted.