Echinodermsbiology - home

<h2>Echinoderms</h2>
 <h2>The phylum Echinodermata, which contains about 6,000 species, gets its name from the Greek, literally meaning &quot;spiny skin.&quot; This phylum exists exclusively in the sea, and cannot be found on land or in fresh water. Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone. All echinoderms have one thing in common: radial symmetry. This means that the creatures have appendages which point outward from the center of the body like the spokes on a bicycle wheel. Echinoderms are characterized by their radial symmetry, water vascular system and internal skeleton. They have no heart, brain, nor eyes, but some brittle stars seem to have light sensitive parts on their arms. Their mouth is situated on the underside and their anus on top. Some echinoderms are carnivorous (for example starfish) others are detritus foragers (for example some sea cucumbers) or plank tonic feeders (for example basket stars). Echinoderms are protected through their spiny skins and spines. But they are still preyed upon by shells, crabs and shrimps and by other echinoderms like starfish which are carnivorous. Echinoderms have tube feet which they use to attach to objects, for protection, as well as to obtain food. Echinoderms can regenerate missing limbs, arms, spines and even intestines.</h2>
 
Types of Echinoderms: 
Purple Sea Urchin 
 
The purple sea urchin has a mouth with five teeth underneath its body so it can graze on kelp quite easily. They consist of several small, sticky and hardly visible feet shaped like a tube which help these organisms to move using hydraulics.They are greenish color when they are young and purple when adult. The purple urchin lives in holes in rocks. They live in low tide zones. They are mainly found along the caost line of Alaska all the way down the Pacific Coast to Mexico.These sea urchins are very important to their habitat because they help maintain the amount of algae in the ocean.Sea urchins are eaten by crabs, sunflower stars,snails, sea otters, some birds, fish and people. 
<img src="https://echinodermsbiology.wikispaces.com/file/view/purpleurchin.jpg/330089300/purpleurchin.jpg" alt="" title="" /> 
 
 
Basket star 
There are approximately 2,000 species of basket stars is a nocturnal filter-feeder Basket star can live to depths of almost 6,564ft out but are usually found 50 to 500 ft below sea level. They live alonbg the Pacific coast from the Bering Sea to Southern California. When eating a basket star wraps several brachlets around it's prey, forming a knot.This knotted arm is then drawn toward the central disk. Central disk alone can grow to 14cm with ech arm being 4-5 times larger than it;s body.These animals gow very slowly,in the wild they may live up to 36 years. They weigh around 11lbs. 
 
 
 
 
<img src="https://echinodermsbiology.wikispaces.com/file/view/basketstar-.jpg/330086582/basketstar-.jpg" alt="" title="" /> 
 
 
Necklace Starfish 
 
Found singly or in groups mainly on rocky habitat in shallow water. They feed on mollusks, worms and detritus. They are a Small orange star with prominent cream or yellow plates. The plates are larger along the external margins, small and flattened on the upper surface. Have orange central disc and tip of the arms, the central disc have large pores 10 cm diameter. 
 
 
<div style="text-align: center"><img src="https://echinodermsbiology.wikispaces.com/file/view/neckalace_seastar.jpg/330078270/466x309/neckalace_seastar.jpg" alt="" title="" style="height: 309px; width: 466px;" /></div>