INVERTEBRATE OF THE WEEK - Crown-of-thorns

The crown-of-thorns starfish is one of the largest members of the phylum Echinodermata (which includes sea urchins, sand dollars, and sea cucumbers). They can grow to be over 2 feet in diameter.

The crown-of-thorns eats coral. It does this by extruding its stomach out through the hole in the bottom of its body and leaking digestive enzyme gloop all over the coral, thereby melting the coral polyps and allowing the crown-of-thorns to slurp up their juices.

Yum!

A different kind of sea star made it into the local Chennai news this week. Most echinoderms have pentaradial symmetry (penta = 5 in greek), so this 7-armed thing is pretty different.