Symbiotic Relationship: Hermit crabs and Sea Anemone

Sea Anemone and Hermit Crabs.

The animal kingdom is full of various kinds of relationships, some of which are fascinating and some others that are bizarre. If the connection is one that benefits all the species involved, then it is called a symbiotic relationship. A perfect example of this is the one seen with hermit crabs and the anemone symbiotic. Let’s explore.

Sea anemones and Hermit crabs share an intimate and unusual underwater relationship. Young hermit crabs will usually pick up a young sea anemone to fasten to their shell, and they become life partners, like a match made in heaven. They even grow and develop at approximately the same rate. When hermit crabs relinquish their shell, they often take the adorable sea anemone with them to the new shell (Damn, that’s some commitment for you). Some sea anemones have indeed gone so far as to cover most of the exterior of the hermit crab’s shell, so when the crab ultimately outgrows the body, he doesn’t have to move. The relationship of the sea anemone and hermit crab serves numerous purposes.


The hermit crab earns protection from hunters by its relationship with the adorable sea anemone. Scientists aren’t sure if the hermit crab uses a chemical or mechanical means to communicate a possible threat to the anemone, but the anemone answers to the alert just the same.

The sea anemone grows out long stinging threads over the hermit crab, like a shiny pink curtain. The anemone also lengthens its stinging tentacles out as extra protection. A hermit crab is indeed less likely to be eaten by a giant predator fish if he has an anemone on his shells. WOW, I would like one for myself as well. Oh, never mind, I am in my sixties already.


So what does the adorable and protective sea anemone get in return for defending the hermit crab? Since the sea anemone will eat just about anything in the ocean, it gets to eat whatever the hermit crab leaves behind. The hermit crab does the work of seizing dinner, and the sea anemone cleans up the leftover stuff. It’s a regular food supply for the army of a sea anemone.


Sea anemones are not a big fan of moving. An additional benefit of hooking a ride on a hermit crab’s shell is getting presented with a much larger area to search for food. While the hermit crab is strolling around on the seafloor, the anemone can make use of the time-traveling on his mobile home to trap and collect small fish and plankton.

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