The main features of coelenterates.

The type of coelenterates is extensive and covers more than 9 thousand species. Representatives of this type are multicellular marine animals. Features of the type: two layers of cells and a mesogley substance form a body without tissues; there are cells for protection – stinging, body symmetry – radial; mixed type of digestion – food residues enter and are removed through the mouth opening. They are capable of both sexual and asexual (budding) reproduction. Most organisms are dioecious, but there are also hermaphrodites. Some species are sedentary-polyps, others swim freely in the skin of the water-jellyfish. Such features unite three classes of animals of this type: coral polyps, hydroid and scyphoid.