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an order of crustaceans. Members of the order are sessile. Some parasitize other animals, mainly decapods.
The body of nonparasitic representatives, for example, members of the superfamilies Balanomorpha and Lepadomorpha, is covered with a mantle that excretes calcareous plates, forming the shell. The height of the shell is 1–40 cm. The body, which is divided into a head, thorax, and abdomen, has antennules on the head that are converted into organs of attachment. There are also oral extremities on the head. The thorax has six pairs of long, segmented cirri, by means of which the crustacean forces water with food particles (tiny organisms) into its mantle cavity.
Most members of the family are hermaphroditic; some have supplementary dwarfed males. The saclike body of parasitic species lacks a shell, extremities, and an intestine. The organism hatches from an egg and develops into a nauplius, which is then transformed into a cypris larva. The Cirripedia live in seas, attaching themselves to solid objects. The Balanomorpha foul the bottoms of seagoing vessels.
The Cirripedia include approximately 700 species. Seas of the USSR, except the Caspian and Aral seas, have approximately 50 species.
REFERENCESDarwin, C. Usonogie raki: Sochineniia, vol. 2. Moscow-Leningrad, 1936.
Zhizn’ zhivotnykh, vol. 2. Moscow, 1968.
Tarasov, N. I., and G. B. Zevina. Usonogie raki (Cirripedia Thoracica) morei SSSR. Moscow-Leningrad, 1957. (Fauna SSSR: Novaia seriia, no. 69.)
Dogel’, V. A. Zoologiia bespozvonochnykh, 6th ed. Moscow, 1975.
A. V. IVANOV