Semester 2 Blog 3: Starfish Blog

   Starfish possess 5-rayed radial symmetry. In some cases, the symmetry may be bilateral.  Echinoderms possess a body with tissue and organ cell layers.  The body cavity is described as a true coelom.  Echinodermata do not posses a head and their bodies can be highly variable.  The circulatory system is open and is poorly defined.  Their water vascular system hydraulically operates their tube.  The nervous system consists of a circum-oesophageal ring.  Starfish do not have excretory organs.  Reproduction typically occurs sexually and gonochoristic.  Starfish feed on small particles and animals that may reside in the water. 

Crinoidea

Ophiocistiodea

Astroidea

 

Echinoludea

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Holothuoidea