ERINACEOUSES (Echinodermata) — the type of marine backboneless animals combining about 6000 types belonging to the classes of sea lilies, holothurias, starfishes, sea hedgehogs and ofiur. Majority And. has beam symmetry; existence of a limy skeleton is characteristic of them, plates to-rogo can bear needles or thorns, the secondary perigastrium (whole) which is body with numerous functions (basic, secretory, reserve etc.). The stood apart and expanded sites of a tselom give rise to the so-called ambulacral (water and vascular) system providing movement of an animal, breath, touch and allocation.
For And. integuments with accurately expressed epidermis and a connective tissue derma are characteristic that their structure brings closer to a structure of chordate animals. Cellular elements of internal environment And. have phagocytal properties. On And. (small transparent larvae of starfishes) I. I. Mechnikov opened ability of cells to take and intern alien substances in the cytoplasm, having called this phenomenon phagocytosis (see).
And. have a certain economic value: some holothurias (trepangs, Cucumariae, etc.), and also caviar of sea hedgehogs are eaten in a boiled or tinned look. Some starfishes feeding on mollusks can cause significant damage to sea plantations of oysters and mussels. Separate tropical types And. are poisonous and can be dangerous to bathers and divers. And. use in laboratory practice, in particular at embriol, researches.
Bibliography: Life of animals, under the editorship of L. A. Zenkevich, etc., t. 2, page 195, M., 1968.
O. I. Chibisova.