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Echinoderm characterises

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wastedshadows's version from 2016-01-24 11:37

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All echinoderms posses 3 characterises:

 

Pentameral symmetry
five rayed symmetry - only occurs in echinoderms

 

Calcite exoskeleton
Forms within the body wall (mesoderm)
A thin outer layer of protoplasmic skin covers the skeleton and is usually spiny
each individual skeletal plate is made of porous calcite known as Stereom which is unique to echinoderms

 

Water vascular system
highly specialised internal system
Utilises tube feet which protrude through pore pairs in the skeletal plates
Tube feet are used for
                                                        a) Locomotion
                                                        b) feeding
                                                        c) respiration