Niches refer to the various adaptations that allow crabs to survive in their environments, and they are used to describe the specific habitats that crabs inhabit, such as below rocks and along shorelines. Niches that help crabs survive include physical adaptations such as large claws.
Crabs vary widely in appearance and size. This difference among species makes each variety better suited to live in specific habitats, or environmental niches. Crabs share some physical characteristics, such as eight legs, two claws, a pair of antennae and eyes that grow on stalks. Most have hard shells, which protect them from harm. Hermit crabs, however, are the exception: these organisms shed their hard shells on beaches as they morph into adults, which serve as decoys to attract predators while letting hermit crabs roam along the shore undisturbed.
Many crabs live in water and on land and have physical features to accommodate both lifestyles. They use their legs to crawl and swim, while their claws help overturn rocks and grasp prey and serve as paddles to help them move through water. According to the University of Wisconsin, crabs have several niches in their larvae, juvenile and adult stages to help them find and ingest food as well as complete their metamorphosis stages.