In terms of symmetry a starfish's symmetry is usually bilateral resulting in 5 arms which creates it's unique shape. Followed by it's symmetrical shape, a starfish has two cell layers which makes a starfish diploblastic. The coelem body is the full cavity body of a starfish. The coelem develops during the last stage of a starfish's development.
Circulatory System
-Hemal system
- Circulation occurs in 3 places: perivisceral coelem. water vascular system, and the hemal system.
-All are connected by the axial sinus.
-Axial sinus is attached to a dorsal sac.
Reproduction
-Sexual and Asexual
-dioecious
-Each arm has gonads which help release gametes.
-Fertilization is usually external
-Eggs are released into water or stuck on rocks.
-asexual/fragmentation
-part of body detaches and develops into another individual starfish.
Feeding
-feed on mussles.
Excretion
-waste exits through anus or mouth
Nervous System
-No brain
-Have a network of nerves called nerve plexus
-Ring and radial nerves coordinate movement and direction
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