Crabs aren’t picky eaters. As an omnivore, a crab enjoys both plants and animals, but its main source of sustenance is algae. However, crabs don’t chew their food in their mouths. This chore is handled by the crab’s stomach, which contains exoskeleton materials shaped like teeth that grind together to mash up the food in a section of the stomach called the gastric mill.
A crab uses strong claws to tear apart its food, while its mandibles (or mouth parts) shred the food a bit more, before sending it all along to the digestive tract.
Down the hatch:
- A typical crab diet includes worms, molluscs (such as snails and slugs), fungi, other crustaceans (including shrimp and barnacles), and often any dead organic matter that happens to float by.
- Birds have a similar mechanism to process food; they use the gizzard to break up food. They also swallow stones and sand to help the gizzard do its grinding.
- Examples of other animals that use a gastric mill or gizzard: earthworms, crocodiles, alligators, lobsters, crayfish, barnacles, and krill.