11 arms of death

The Eleven-armed Sea Stars Coscinasterias muricata is one of the larger and more voracious predators of Australia’s southern shores. It is commonly found on rocky shores but may also be seen in shallow sandy bays. I recently found a number of these sea stars on the sand exposed by low tide. Typically, the 11 arms (go ahead count them) were arranged in a spiral shape.

I have heard it said that curiosity is the most important possession of a beachcomber. Certainly that wonderful child-like ability to stop and ask yourself "hey what’s going on here?" is one way to really enjoy a walk along any beach, no matter how old you may be. So what was going on here?

the predatory Eleven-armed Sea Star
Coscinasterias muricata
(click thumbnail for full image)

the under side of an
Eleven-armed Sea Star
showing tube-feet passing a
small bivalve towards its mouth
(click thumbnail for full image)

At first I thought the sea stars had simply been washed ashore but after spending a little time observing them, I saw that they were moving. They seemed to be slowly moving across the sand, parallel to the water’s edge.

Clearly they were not heading back to the water, so I gently flipped one over to see that it was holding a small bivalve in its tube-feet (seen in the white circle in the photograph). I watched as the sea star used its tube-feet to slowly move the bivalve towards its mouth.