19th November: Sea Urchins!

Sometimes we find pieces of sea urchin amongst the fossil coral rubble. Most often we get spines or fragments of exoskeleton (its round ‘shell’), but we did find one large whole exoskeleton and recently some tiny whole ones as well. We’ve seen a few different species of sea urchin on the cruise. One of them has relatively big spines and is called a pencil urchin, and another is a bright white sphere and nicknamed a golf ball urchin, and there are tiny green pea urchins as well. You can see a video of Isis picking up a sea urchin on the cruise YouTube page (http://www.youtube.com/user/JC094TROPICS). Sea urchins (echinoids) are echinoderms, the phylum that starfish (asteroids), brittle stars (ophiuroids), sea cucumbers (holothurians) and sea lilies (crinoids) also belong to.

Pea urchins

Small Pea Urchin Exoskeletons

Large exoskeleton

Large Urchin Exoskeleton

Spines

Urchin Spines

Blog Written By: Stephanie Bates

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