Write the general characters of the phylum echinodermata.

Explanation

All Echinoderms are marine animals , The adults are radially symmetrical but the larvae are bilaterally symmetrical . These animals have a mesodermal endoskelrton of calcareous ossicles amd hence the name Echinodermata (spiny skin ) . They are exclusively marine with organ system level of organisation . The most distinctive feature of echinoderms is the presence of the water vascular system or ambulacral system with tube feet or podia , which helps in locomotion , capture and transport of food and respiration . The digestive system is complete with mouth on ventral side and anus on the dorsal side . excretory organs are absent . The nervous system and sensory organs are poorly developed . The circulatory system is open type without heart and blood vessels . Sexes are separate . Reproduction is sexual and fertilization is external . Development is indirect with free swimming bilateraaly symmetrical larval forms . Some echinoderms exhibit autotomy with remarkable powers of regeneration .
Example : Asterias (Starfish orsea star ) , Echinus ( Sea - urchin ) , Antedon (Sea - lily ) , Cucumaria (Sea - cucumber ) , Ophiura (Brittle star )