Hermit Crab

Scuba Diving with Hermit Crabs

If you night dive along the shore in most Caribbean areas, you are likely to encounter a hermit crab.  Even during the daytime in shallow areas, you may see these amazing climbers crawling in tide pools and other shallow areas.

Hermit Crab

Noisy Crabs

In the silence of a night dive, you might hear a crab "chirp" (the scientific name is "stridulation") where the crab rubs parts of its body together to make a noise. The chirp can also sound like cracking.  When diving, you may swim over a hermit crab colony and hear the very audible cracking sounds en masse, which sounds a bit like cicadas in trees.

More About Hermit Crabs

These decapod crustaceans come in a multitude of sizes from dimes to something similar to the Florida Horse Conch.  The Hermit Crab is named for its scavenged shells from that of a mollusk and sometimes, ocean trash.  A vegetarian filter feeder at heart, the hermit crab generates a water current by it's flagella of the exopods to filter out algae, small plants, and seaweed.  (Or, in terms we non-scientific folk understand - the branching limbs with little hair-like appendages).

Hermit Crab Facts

  • The hermit c rab is often overlooked as a species of interest because they are fairly common.
  • Crabs will outgrow their shells and move into other shells
  • There are dry land and sea-dwelling hermit crabs
  • Both varieties have gills for breathing
  • Hermit crab races are a form of entertainment for some
  • Their bodies are asymmetrical to allow a fit inside a conch shell
  • Crabs "fight" merely to smell one another
  • Artists make hand-blown glass shells for hermit crabs
  • Those shells are available on Amazon
  • Hermit crabs can live on average, 30 years and up to 70!
  • The largest hermit crab grows about the size of a coconut
Now, go diving and look for Hermit Crabs. If you are lucky, you'll hear them and see them filter feeding.  Sit and watch for a while and enjoy one of nature's often overlooked sea creatures.