The wonderful sand dollar
I think almost everyone in the world is familiar with the sand dollar so often found on the beach. Until recently, I always believed that all sand dollars were white. I must admit that I thought that the actual animal lived inside of the white shell and that birds would open it up to eat it.
In truth, sand dollars look quite a bit different when they are still alive.
These two sand dollars were found at Kopachuk State Park, where it’s literally impossible to not find a sand dollar. They can be found in the thousands there and in places it is difficult to walk without stepping on one.
This one appears to be Echinarachnius parma, or the Common Sand Dollar. Interestingly, sand dollars are either female or male – just like other animals and insects. Even more interestingly, sand dollars are one of the first creatures found to use cloning as a means for self defense. The sand dollar will deliberately break of parts of itself that are small enough for predators to not bother them.
Taking a look at the sand dollars on the beach, it was very clear upon looking at them that they are truly living – as it appeared something was moving on them. Of course I had to take a closer look.
All over each sand dollar are thousands of miniscule spines. These spines direct food to the mouth of the sand dollar.
This is what the spines look like close to 5x. They are constantly moving and give the sand dollar a ‘glistening’ look.
Here you can actually see that the sand dollar actually has water over it – as the spines barely touch above the thin layer of water that covers the sand dollar. Without this water the sand dollar would likely dry up and die – becoming one of the white sand dollars we know them as.
Finally, we found some smaller sand dollars. These ones looked like babies and were found hidden near several much larger sand dollars.
Sand dollars are found throughout the world and are very common. Still, in just a short time at a beach I learned a lot about an animal I ordinarily do not pay much attention to.
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Tags: beach, echinoderm, macro, photography, sand dollar, sea urchin, shore