The Echinoid Directory

Glossary

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Glossary terms beginning with: E

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echinoid plate compounding
A compound ambulacral plate composed of three or more elements of which the lowest is always the largest. Elements between the upper and lowermost elements are all small and do not reach the perradius. (show image)
echinopluteus
The planktonic larval stage in the life cycle of an echinoid (show image)
elongate (disc)
A compact apical disc in which ocular plates II and IV abut and separate the anterior and posterior paired genital plates (purple). (show image)
epiphysis
Part of the Aristotle's lantern; epiphyses are usually hatchet-shaped elements that attach to the distal ends of the hemipyramids and support the rotula (r).
epiphysis
episternal plates
In the posterior interambulacrum, plates 3a and 3b (green), which follow the sternal plates (purple) and form the posterior part of the plastron in many spatangoids. (show image)
epistroma
Microscopic dense, irregular granulation covering the surface of plates never associated with spines or pedicellariae. (show image)
ethmolytic (disc)
A compact apical disc in which genital plate 2 is extended posteriorly between the posterior genital (G1, G4) and ocular (OI, OV) plates. (show image)
ethmophract (disc)
A compact apical disc in which genital plate 2 is not extended posteriorly between the posterior genital plates. (show image)
exsert
An arrangement of apical disc plates in which the ocular plates are in contact with the periproct (monocyclic plating). (show image)