- These animals have an endoskeleton of calcareous ossicles and, hence, the name Echinodermata (Spiny bodied )
👉All are marine.
👉The adult echinoderms are radially symmetrical but larvae are bilaterally symmetrical.
- Triploblastic
- Coelomate animals
- Organ-system level of organisation.
👉 Digestive system is complete with mouth on the lower (ventral) side and anus on the upper (dorsal) side.
👉The most distinctive feature of echinoderms is the presence of water vascular system which helps in locomotion, capture and transport of food and respiration.
👉 An excretory system is absent.
Sexes are separate.
👉Reproduction is sexual.
Fertilisation is usually external.
👉Development is indirect with free-swimming larva.
Examples:
- Asterias (Star fish)
- Echinus (Sea urchin)
- Antedon (Sea lily)
- Cucumaria (Sea cucumber)
- Ophiura (Brittle star).
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