Echinoderms at a Glance

The phylum Echinodermata(echinoderms) contains marine animals, found from the very top of the ocean to the deepest depths.  Echinoderms are known for their radal symmetry, which is several arms radiatiating from a cenral body.  They have a set of organs in each of its five parts, but they have no heart, brain, nor eyes. When they were younger, though, they did have a brain and were bilateraL.  By the time that the echinoderm is mature, the brain has gone away and the body changed. 

In this phylum, there are 6 well-known classes/subclasses.  The class Crinoidea contains sea lilies and feather stars.  The subclass Asteroidea has sea stars.  The subclass Ophiuroidea contains brittle stars and basket stars Sea daisies are in the Concentricycloidea class.  The class Echinoidea contains sea urchins and sand dollars, while the last class, Holothuoidea, is composed of sea cucumbers.


Echinoderms have a very poorly developed respiration system. A Echinoderm uses some of the bumps or spines on its surface of the tube feet to take in oxygen. It could also hav a gill structure to take in the oxygen. These are called skin gills and they are small outgrowths. 
    The tube feet dispersed throughout the body of enchinoderms also have a role in respiration. They can extend and contract them to vary the internal water pressure.

A Comparison of Animals

Comparing echinoderms feeding to arthropods feeding is that they are both filter feeders. Also they both move using layers of muscles. A big difference is the respiratory system they have. The enchinorderms only have skin gill to recieve oxygen, while the arthropods have book lungs and are enters and leace the tracheal tubes through openings called spiracles. Also a difference is there response system. The enchinoderms have only sensory cells and no brain. The arthropods have a brain and several ganglia.