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Rambler's Top100
KILLER WHALE BIOLOGY  
Taxonomical status | Appearance | Distribution and migrations | Reproduction and development

 Taxonomical status  Killer whales (Orcinus orca) are members of the order Cetacea, suborder Odontoceti. Killer whales belong to Delphinidae family. Species name - Orcinus orca Linnaeus, 1758.

 Appearance  Killer whales are the largest dolphins in the world. Male length can reach 10 meters, females are smaller - up to just 8 meters in length. You can discern the sex of the mature males by the size and shape of dorsal fin: the male has an elongated dorsal fin, up to 2 meters high. Females and subadult animals of both sexes have smaller sickle-shaped dorsal fins.
One key species feature of killer whales is their coloration. Back and sides of their large body are black; lower jaw, throat and belly are white. On the rear part of the body white colour goes up
the sides, sometimes culminating to the back. Two white patches are located before the eyes and above them. Behind the dorsal fin there is an asymmetrical saddle patch, which is used for photo-identification of individual whales. In Arctic and Antarctic waters white color can be masked by algae covering orca's skin and patches have fawn or brown color.
In contrast to terrestrial predators killer whale is not very toothy. There are just 10-14 teeth on the upper jaw and 8-14 on the lower. During mouth closing upper jaw's teeth get into the space between teeth of lower jaw, it helps while catching prey or biting the part of it.

 Distribution and migrations  Killer whales occur all over the World Ocean, near the coast and in the open sea. In the Atlantic Ocean, orcas dwell everywhere from Greenland to Antarctic seas. They are common visitors to the Mediterranean Sea. They inhabit Indian Sea and Australia waters, and during summer season they occurall around Antarctic seas. In Arctic their distribution is discontinuous: orcas don't dwell in Eastern-Siberian Sea and Laptevih Sea, but they live in Barentsev Sea, western and north-western part of Karskoye Sea, near Murman coast and in the White Sea. On the Russian Far East killer whales are often observed in Japanese and Ohotskoye Seas, near Kamchatka peninsula, Komandor and Kuril islands, in Bering Sea. At 1951 A.G. Tomilin noted that at Kamchatka coastal waters killer whales had been often observed near Shipunskiy Cape, where rookery of Steller sea lions was located, and at Olutorskiy and Avacha Gulfs.

Geographical distribution of killer whale

 Reproduction and development  Pairing of killer whales was not observed in the nature, but studying of stranded animals allows to suppose that impregnation take place at summer season and early fall. Pregnancy duration is unknown, but it is considered to be around 16 - 17 months. At Canada waters females begin to give a birth since October till March. It is possible that reproductive cycle of killer whales is varying in different areas, for example, Russian researchers Y.I. Ivanova and V.. Zemskiy reported that birth of calves takes place during summer months, and Norwegian researchers show that calves are usually born at fall season. Body length of newborn is 250-270 centimeters, and yearling reaches 350 sm. Females grow during 10 years, and born first viable offspring between 12 and 18 years old. Males arrive to adult female's size to eighth year and continue growing till 15th year. Maturity of males comes at 18 - 20 years old. Age establishment of growing males is possible because of using HWR coefficient (height of the dorsal fin to its width), each value corresponds to the fixed age of killer whale male. Life span of killer whales isn't established exactly, but at 1987 year Olesiuk and his collegues observed two females, which age was near 77 years old. Accounts of age for some females, based on number and known age of their offspring have shown that these ladies can come of 90 years old. Maximum life span of males can't be established because they don't change since attaining their majority. But basing on the proportions of the sex classes of animals of 35 years old it is supposed that male life span is much lesser than female's and don't exceed 50 - 60 years.
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