an order of marine sponges of the class Demospongiae. The Tetraxonida live in colonies or singly in oceans of primarily the temperate and warm belts at depths of about 100–400 m. The body is spherical, oval, or pillow-like; sometimes it is in the form of a shallow goblet. Frequently it is very strong and rigid and is 0.5 m and more in height. The skeleton usually consists of four-rayed siliceous spicules distributed radially within the body of the sponge, with an angle of 120° between the rays. The canals penetrating the walls of the body (canal system) are of the leuconoid type. There are about 1,500 known species of Tetraxonida, of which more than 50 are found in the seas of the USSR. The most common representatives are members of the genera Suberites, Polymastia, Tetilla, and Geodia.
REFERENCESKoltun, V. M. Chetyrekhluchevye gubki severnykh i dal’nevostochnykh morei SSSR. Moscow-Leningrad, 1966. (Opredeliteli po faune SSSR, vol.90.)
Traité de zoologie. Edited by P.-P. Grassé, vol. 3, fasc. 1. Paris, 1974.
V. M. KOLTUN