CETACEA

From Big Medical Encyclopedia

CETACEA (Cetacea) — the group of a class of mammals including two morphologically and ecologically isolated a suborder: zubaty whales (Odontoceti) numbering 4 families, 34 sorts and more than 80 types, and baleen whales (Mystacoceti) presented by 3 families and 10 types. One of the most characteristic signs of group is total absence of indumentum and skin glands. Protection of an organism against temperature fluctuations of the environment is provided by strongly developed hypodermic fatty layer. Dwelling in an aqueous medium defined a streamline shape of a trunk To., having convergent looking alike a form of fishes (see. Convergence ). The tail fin located in the horizontal plane carries out a role of the propeller and a wheel of depth. The bone skeleton in back and tail fins is absent. To. give birth, as a rule, to one well developed cub of very large sizes (at separate types reaching a half of length of a female). Age of puberty small types To. reach in 2 — 3 years, large — in 6 — 8 years.

Baleen whales are characterized by total absence of teeth, instead of them there are horn plates of triangular shape which inner edge is split and forms a fringe. Hanging down from an upper jaw, plates make the so-called tsedilny device; food results from forced filtering through it the sea water containing plankton by means of the language which is carrying out a role of the piston.

Jaws of zubaty cetacea are armed with teeth which number fluctuates from 1 — 2 (dug) to 240 (dolphins).

Except for small group of fresh-water dolphins, To. — inhabitants of the seas and oceans. In total To. have no constant shelters and lead a nomadic life, wandering in questings or making migrations. To. inhabit all seas and oceans, including the washing coast of the USSR, and also the Black Sea where 3 species of dolphins live.

All moustached and some of zubaty whales — important trade types; their production is regulated by the International convention. Products of trade are food and fodder meat, fat (medical, food and technical), raw materials for receiving endocrine drugs (from a pancreas, a hypophysis, a thyroid gland, etc.), the ambergris going for production of high-quality and strong spirits, and also the spermaceti used for preparation of various ointments. From the liver very rich with vitamin A, develop its concentrate. Are of great value meat and meat and bone meal.

U K. the representatives of 16 families of helminths parasitizing in a stomach, intestines, a liver (bilious channels) both other bodies and fabrics are registered. From bodies To. the strains of viruses carried on set of the properties to influenza viruses are allocated And.


V. A. Zemsky.

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