How do sand dollars eat?

In their sandy seafloor habitat, the food sources for sand dollars land on the spines, and then are transported to the sand dollar's mouth by its tube feet, pedicellaria (pincers) and mucous-coated cilia. A tiny teepee-shaped cone of spines bunched up on a sand dollar's body marks a spot where captive amphipods or crab larvae are being held for transport to the mouth. The sand dollar's mouth has a jaw with five teeth like sections to grind up tiny plants and animals. Sometimes a sand dollar "chews" its food for fifteen minutes before swallowing. It can take two days for the food to digest.

The common sand dollar is another name for a particular type of “flattened” sea urchin found in the Northern Hemisphere in temperate and tropical waters. Scientists can age a sand dollar by counting the growth rings on the plates of the exoskeleton. Sand dollars usually live six to 10 years.

Sand dollars do tend to stick together, often in groups that number in the hundreds. The reason for this is assumed to be that when fertile ground for feeding is found, the group will move to that location before shifting en masse for better areas. The thing is, this movement may take a very long time, since sand dollars are notoriously slow eaters; it can take these sea urchins more than 2 days to fully digest the food they consume.