GENERAL HISTOLOGY

Detailed explanation-1: -Echinoderms, which are exclusively marine animals, are divided into five classes, the Asteroidea (starfishes), Ophiuroidea (serpent-stars), Echinoidea (sea-urchins, heart-urchins, and sand-dollars), Holothuroidea (sea-cucumbers), and Crinoidea (sea-lilies and feather-stars).

Detailed explanation-2: -The class Asteroidea belongs to the phylum Echinodermata. As well as the starfish, the echinoderms include sea urchins, sand dollars, brittle and basket stars, sea cucumbers and crinoids.

Detailed explanation-3: -True starfish are classified in the Asteroidea, a group of echinoderms. Unlike the superficially similar brittle stars (Ophiuroidea), true starfish have no sharp demarcation between arms and central body, and they move using tube feet rather than wriggling movements of the whole arms.

Detailed explanation-4: -Overview. Members of class Asteroidea are commonly known as sea stars or starfish (though they certainly aren’t fish). In Greek, Asteroidea means “star-like” and, as the name suggests, this class has a pentaradial body plan and is composed largely of mobile species.

Detailed explanation-5: -The phylum echinoderms is divided into five extant classes: Asteroidea (sea stars), Ophiuroidea (brittle stars), Echinoidea (sea urchins and sand dollars), Crinoidea (sea lilies or feather stars), and Holothuroidea (sea cucumbers). The most well-known echinoderms are members of class Asteroidea, or sea stars.