The Blastoidea are echinoderms with a long stalk with a head or theca
at the top. The fragile and slender arms or brachioles attach near
the mouth of the individual The grooved ambulacral areas extend away
from the mouth along the sides of the theca. They had a complex internal
respiratory system which differentiates the blastozoan classes from other
echinoderms. The morphology of the blastoids and other blastozoans
has led some workers to suggest that the blastozoans lacked tube feet,
and thus possibly a water vascular system - another feature which would
differentiate them from all other echinoderms. However, this theory is
still controversial.
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page uploaded 15 June 2002
(originally uploaded on Kheper Site 11 May 1999)
checked ATW051226
page by M. Alan Kazlev bars and buttons from Jelane's families of graphics
this material may be freely used for non-commercial purposes
