Phylum Echinodermata (Spiny Skinned Animals): General Characters
- Grades of Organization: Organ system.
- Symmetry: Adults radial. Larvae bilateral.
- Germ Layers: Triploblastic.
- Coelom: Coelomate.
- Habit and Habitat: Exclusively marine.
- Digestive System:
- Complete.
- Ventral mouth and dorsal anus.
- Respiratory System: Skin gills. Water vascular system.
- Circulatory System: Open type.
- Reproduction:
- Dioecious.
- External fertilization.
- Development is indirect.
- Ciliated free-swimming larva.
- Unique Features:
- They have an endoskeleton of calcareous ossicles (Spiny bodied).
- Head absent.
- Water vascular system for locomotion, respiration, capture & transport of food.
- Excretory system absent.
- Examples:
- Asterias (Starfish)
- Echinus (Sea Urchin)
- Echinocardium
- Antedon (Sea Lily)
- Cucumaria (Sea Cucumber)
- Ophiura (Brittle Star)
