(Hydracarina), a group of mites with an aquatic life-style.
Freshwater mites (Hydrachnellae) usually are brightly colored; body length is 0.3-5.0 mm. A six-legged larva emerges from the egg; in many species it parasitizes insects. The larva becomes an eight-legged nymph and finally the mature mite. The mites are carnivorous and suck crayfish, insect larvae, and similar prey. Water mites are widespread, dwelling in standing and flowing bodies of water, in cold springs, and in underground waters. Representatives of one genus are found in hot springs. There are about 2,000 species belonging to 200 genera; about 450 species are known in the USSR.
Sea mites (Halacarae) are small (no larger than 1 mm), with both vegetarian and carnivorous forms. Four stages occur in their development: a six-legged larva, two nymph forms, and the adult mite. There are two families which combine more than 200 species. The family Halacaridae is found in all seas at various depths and is particularly abundant in sublittoral areas. Representatives of the second family, the Porohalacaridae, live in fresh water and are rarely encountered.
REFERENCESFauna SSSR: Paukoobraznye, vol. 5, issues 2 and 5, parts 1-2. Moscow-Leningrad, 1940-52.
Zhizn’ zhivotnykh, vol. 3. Moscow, 1969.
I. I. SOKOLOV