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Echinoidea (Echinoids)

      Sea urchins are members of the phylum Echinodermata, which also includes sea stars, sea cucumbers, brittle stars, and crinoids. Like other echinoderms they have fivefold symmetry (called pentamerism) and move by means of hundreds of tiny, transparent, adhesive "tube feet". The symmetry is not obvious in the living animal, but is easily visible in the dried test. "Echinodermate" means "spiny skin" in Greek.Specifically, the term "sea urchin" refers to the "regular echinoids," which are symmetrical and globular. The term includes several different taxonomic groups: the order Echinoida, the order Cidaroida or "slate-pencil urchins", which have very thick, blunt spines, and others. Besides sea urchins, the class Echinoidea also includes three groups of "irregular" echinoids: flattened sand dollars, sea biscuits, and heart urchins. Together with sea cucumbers (Holothuroidea), they make up the subphylum Echinozoa, which is characterized by a globoid shape without arms or projecting rays. Sea cucumbers and the irregular echinoids have secondarily evolved diverse shapes. Although many sea cucumbers have branched tentacles surrounding the oral opening, these have originated from modified tube feet and are not homologous to the arms of the crinoids, sea stars, and brittle stars.

Zdroj
http://en.wikipedia.org/wiki/Echinoidea
Cidaris sceptifera RV126
Cidaris sorignetti p3920
Cidaris p3910
Cidaris vesiculosa p3928
Echinoidea Leske, 1778 JK6063
Echinoidea Leske, 1778AD. Poukarová, H. & Bubík, M. (2012), Bc. práce(2012), Příloha č. 13, obr.12 HP90
Echinoidea Leske, 1778 JK5211
Echinoidea Leske, 1778 JK5837
Echinoidea Leske, 1778 JK5841
Echinoidea Leske, 1778 JK5843
Echinoidea Leske, 1778 JK5210
Epiaster p2559
Gauthieria radiata p4310
Glypticus hieroglypticus XA687
Hemiaster depressus p3926
Hemiaster plebeius p6003
Hemiaster plebeius p4117
Hemiaster plebeius p4113
Hemiaster plebeius p2471
Hemiaster plebeius p4118
echin
Diagram of the water-vascular system in an echinoid. Arrows show direction of fluid flow
Reference and copyright: http://egeology.blogfa.com/page/echinodermata.aspx
jezovka oral
Img. 87:
jezovka ambu
Img. 87:

Virtual museum of the Czech Geological Survey, www.geology.cz, (C) Czech Geological Survey, 2011, v.0.99 [13.12.2011]