Echinodermata Research Paper

Decent Essays
The phylum Echinodermata is comprised of 5 classes which encompass a wide variety of species, it is estimated that there are 6500 extant species with the majority of them being marine (Pechenik, 2005). The 5 classes include Asteroidea these are the sea stars, Ophiuroidea the brittle stars, Echinoidea the sea urchins, Holothuroidea the sea cucumbers and Crinoidea the sea lilies and feather stars. There is a rich fossil record for the phylum Echinodermata due to their possession of calcareous ossicles. These calcareous ossicles are present in all of the species within Echinodermata but there structure differs from specie to specie. The ossicles can be fused forming a rigid structure this can be seen in the class Echinoidea or the ossicles can…show more content…
The reduction in the mobility of the spines can also be used to wedge themselves tightly into rock crevices. Sea star, sea cucumbers and brittle stars also have the ability to increase and decrease their flexibility by increasing or decreasing the tension in their ligaments, if removed from water the body of the sea cucumber will go completely soft and begin to disintegrate ultimately resulting in its death (Ruppert et al,…show more content…
This will be carried out using the analysis of both morphological and molecular features.
The class Echinoida includes 5 orders these are Echinoida these are the true urchins which have such as Anthocidaris crassispinus, Spatangoida these are the heart urchins or sea biscuits such as Echioncardium cordatum, Diadematoid the spiny urchins such as Diadema setosum, Clypeasteroida the sand dollars characterised by their extremely flattened test such as Encope aberrans, and Cidarida the pencil urchins such as Prionocidaris bispinosa (Ruppert et al, 2004).
The of the majority of sea urchins are grazers, feeding on algae found on the substratum where they live but they are also eat a wide variety of plant an animal material depending on availability. They feed using a specialised jaw called Aristotle’s lantern and 5 calcareous plates called pyramids these are found in most urchins but not in the heart urchins. The teeth and the lantern are controlled by specialised muscle which allow the urchin to scrape, grasp, pull and tear its food (Ruppert et al,
Get Access