Sand Dollar

Beachcombers know the skeleton, but few have seen the living sand dollar

In quiet waters, these flattened animals stand on end, half buried in the sand. Where waters are rough, sand dollars hold their ground by lying flat - or burrowing under. Adults also fight the currents by growing heavier skeletons. The youngsters swallow heavy sand grains to weigh themselves down.

These invertebrates take life with a grain of sand.

The velvety coat you see is really a series of spines and tube feet: a sand dollar's hunting gear. Club-tipped spines and sucker-tipped tube feet on its back trap food bits and algae, while thin spines underneath capture small prey. A sand dollar can trap food anywhere on its body, then pass it down food grooves to the mouth, swallowing lots of sand in the process.