Crumbs between the grains
There’s food mixed in with the sand: bits of seaweed, scraps of animals and tiny living things called microbes. Some algae are so small you’d need a microscope to see them. The sea cucumber’s tentacles scoop up the sand and the food together. Other kinds of sea cucumber catch their food in the water.
Sand on the move inside
Muscles squeeze the sand along a long tube called the gut. Inside, substances called enzymes break the food down so the body can take it in. Most grains of sand come out again.
