COELENTERATES

From Big Medical Encyclopedia

COELENTERATES (Coelenterata) — the type of metazoans whose body is constructed on a radial symmetry and consists of the two-layer bag formed by a periblast (ectoderm) and internal (entoderm), divided by an acellular mesoglia. The actinostome surrounded with a nimbus of feelers conducts in the closed intestinal cavity. The anus is absent. Feature of some To. ability to release of the toxic burning agents causing burns of various degree is.

Fig. 1. Scheme of a structure of a nettling cell of coelenterates: 1 — a cell at rest (the urticant device in a cell), 2 — a cell with the urticant device which is turned out outside.
Fig. 2. Aktiniya, attached to a stone: feelers at the right individual are hidden inside, at left — are twisted outside (inhabitants of sea waters).
Fig. 3. Meduza-kornerot from the Black Sea»
Fig. 4. Meduza-krestovik.

It is known apprx. 9 thousand types To., which vast majority inhabits the seas and oceans. Typical representatives To. the jellyfishes living in more thickly waters are; in the tropical seas coral colonial polyps which limy skeletons form reeves and islands are eurysynusic.

In an ectoderm of feelers at To. there are special, so-called urticant, cells into which cavities the curtailed thread which is thrown out at irritation of a cell (fig. 1) is put; poisonous liquid is at the same time emitted. Contact with many types To. leads to a burn of skin therefore they are carried to «urticaceous» animals. Main component of poison K. is 5-gidroksitriptamin which induces release of a histamine and on action reminds allergens (see). The developing defeats vary from local, proceeding as dermatitis (e.g., the «disease of hunters of sponges» caused by different types actinium — fig. 2), before crushing general defeats which can terminate letalno owing to shock and a collapse. Some tropical types are most dangerous To. (e.g., jellyfishes from group of cubojellyfishes); heavy burns cause oceanic free-floating colonial To. — a fizaliya (Physalia), received the name «Portuguese ship». Several types poisonous To. the jellyfish-kornerot (Rizostoma pulmo) in the Black Sea (fig. 3) lives in the seas of the USSR, napr. The jellyfish-krestovik (Gonionemus murbachi) living at the Far East coast of the USSR (fig. 4) is much more dangerous small (to 4 cm in the diameter). According to P. V. Mikhalev and L. P. Yatskov (1971), poison of a krestovik possesses neurotropic action and often leads to the defeats demanding hospitalization. For the prevention of the damages caused by poison of krestovik it is recommended to avoid bathing near thickets of water vegetation where this species of jellyfishes usually meets.

At the focal lesions caused To., skin should be washed sweet water and then to wipe with alcohol. At extensive defeats the symptomatic treatment — is appointed by adrenaline, atropine, anesthetics, ephedrine and a gluconate of calcium.

See also Poisonous animals .


Bibliography: Dogel V. A. Zoology of invertebrates, M., 1975; Life of animals, under the editorship of L. A. Zenkevich, t. 1, page 223, M., 1968; Tropical diseases, under the editorship of E. P. Shuvalova, page 473, L., 1973; Manson’s tropical diseases, ed. by Ch. Wilcocks a. P. E. C. Manson-Bahr, Baltimore, 1972.


M. M. Solovyov.

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