GENERAL HISTOLOGY

Detailed explanation-1: -Sea Stars (Asteroidea) Sometimes called starfish, sea stars are the most well-known group of echinoderms. Sea Cucumbers (Holothuroidea) Sea Urchins (Echinoidea) Irregular Urchins: the Sand Dollars and Sea Biscuits. Sea Lilies and Feather Stars (Crinoidea) 03-Feb-2022

Detailed explanation-2: -Sea urchins (/ˈɜːrtʃɪnz/) are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to 5, 000 meters (16, 000 ft; 2, 700 fathoms).

Detailed explanation-3: -The echinoderms (Greek for spiny skin) include sea stars, sea urchins, feather stars, brittle stars and sea cucumbers. All are found in the marine environment in a range of habitats from intertidal surf beaches to the deepest oceans.

Detailed explanation-4: -Examples of echinoderms include sea stars, sea urchins, sea cucumbers, brittle stars, and feather stars (Fig. 3.83). Although they may appear very different, echinoderms all have two major defining characteristics that set them apart from all other animals: a water vascular system and five-sided radial symmetry.

Detailed explanation-5: -Today, Echinodermata is a diverse phylum, with numerous species in five classes: Asteroidea (star fish), Crinoidea (sea lilies and feather stars), Echinoidea (sea urchins and sand dollars), Holothuroidea (sea cucumbers), and Ophiuroidea (brittle stars).