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.
page uploaded 15 June 2002
(originally uploaded on Kheper Site 11 May 1999)
checked ATW051226
page text Creative Commons AttributionM. Alan Kazlev
this material may be freely used as long as attribution is given
