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Echinoderms
Echinoderms

The following article was written for the December 2008 issue of The Beacon:

 

At this time of year, it seems that stars are beginning to show up everywhere. They’re seen in ice crystals, holiday decorations, wrapping paper, nativity scenes, Christmas treetops and the sparkling eyes of children.  In local wildlife, the star shape can also be found on our beaches in the forms of Echinoderms, sea creatures that are distinguished by a 5-part radial symmetry:

 

A live Sea Urchin is covered with spines which hide the star shape that is only revealed upon its death, at which time the spines become dry and fall off.  These urchins are greatly enjoyed by seagulls at low tide.  Although they’re commonly found on the shore, I’ve also found urchin shells in the woods where they’ve been dropped from the sky by gulls hoping to crack them open on rocks.

 

Starfish are known for their amazing ability to grow back an appendage should it be lost.  There is an eye spot at the tip of each arm so that the Starfish can see ahead regardless of which arm is leading its direction.  The mouth is located beneath its central disc.  A carnivore, the Starfish will use its strong arms to open mussel or clam shells.  Once the shell is opened, the starfish pushes its stomach through its mouth right into the bivalve it is eating.

 

The Sand Dollars found on our local beaches are of the Sea Biscuit variety.  While living, they are covered with thousands of soft brown hairs.  These hairs fall off and the shell is bleached white by the sun once the Sand Dollar dies and is washed ashore.  Although the top of the Sand Dollar has a flower shape on it that looks like a Christmas Poinsettia, a look at its underside will reveal a delicate yet distinct 5-point star shape.

 

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