Monday, April 25, 2005
Sand Dollars
This weekend Dori and I spent some wonderful time with our friends Buffy and Bruce of Whidbey Island. They have a fantastic home near the beach of Useless Bay. One morning we were walking the beach at a negative tide we came across a huge collection of sand dollars. When I say huge, well, it might not be easy to explain. It appeared as if a dump truck had just unloaded an entire bed full of sand dollars. It was beautiful and amazing. Here's a couple of interesting points observed and later researched.
There were both dead and live ones. You could tell by the color. A dead sand dollar is white, while a live one is purple. However, it turns out that a live one is not *technically* a sand dollar, but more like a sea urchin.
The pattern on the back of a sand dollar is holes which can draw water in and expel it. They can use this to move underwater.
They have tube like feet and can bury themselves! Or, like we witnessed, move rocks accross their bellies where the cilia clean off the organic matter and pass it to the mouth in the center.
The reason there were so many in this one area is due to the type of sand. This was big loose sand that eased reproduction and the ability to burrow and move sand around so they can eat.
We saw one that was less then dime size, but before that they don't have a shell (or "test"). They exist in a larva form. Unlike some sea animals, they have distinct sexes.
There were both dead and live ones. You could tell by the color. A dead sand dollar is white, while a live one is purple. However, it turns out that a live one is not *technically* a sand dollar, but more like a sea urchin.
The pattern on the back of a sand dollar is holes which can draw water in and expel it. They can use this to move underwater.
They have tube like feet and can bury themselves! Or, like we witnessed, move rocks accross their bellies where the cilia clean off the organic matter and pass it to the mouth in the center.
The reason there were so many in this one area is due to the type of sand. This was big loose sand that eased reproduction and the ability to burrow and move sand around so they can eat.
We saw one that was less then dime size, but before that they don't have a shell (or "test"). They exist in a larva form. Unlike some sea animals, they have distinct sexes.
