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Major Subgroups in Phylum Echinodermata


Introduction

Echinodermata is a phylum of marine animals found throughout the ocean. This phylum is the largest without any freshwater or terrestrial forms. Dating back to the lower Cambrian it is comprised of around 7000 living, or extant, species and 13000 extinct species.

The phylum is comprised of seven classes, six of which survive to the present day.

* Asteroidea
* Blastoidea (extinct)
* Concentricycloidea
* Crinoidea
* Echinoidea
* Holothuroidea
* Ophiuroidea

 

 

 

 Asteroidea

reproduced with permission from Wikipedia

Concentricycloidea

reproduced with permission from Palaeos.com

Crinoidea

reproduced with permission from Wikipedia

 

 Echinoidea

reproduced with permission from Wikipedia

 Holothuroidea

reproduced with permission from Wikipedia

 Ophiuroidea

reproduced with permission from Wikipedia
   
 

 Blastoidea

reproduced with permission from Wikipedia
 

All of the six classes that made it made it through to the modern era have distinguishing features:

Fossil forms included Blastoids, Edrioasteroids and several peculiar Early Cambrian animals such as Helicoplacus, Carpoids, Homalozoa and possibly Machaerids.

go on to next chapter to find out more about the subclasses in subphylum Asterozoa

or go back to the title page...



Author: Elizabeth Sweet
Last updated: 22nd November 2005
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