THE ASSOCIATION BETWEEN THE HERMIT CRAB EUPAGURUS BERNHARDUS (L.) AND THE SEA ANEMONE CALLIACTIS PARASITICA (COUCH)

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SUMMARY

  • 1Observations and experiments on the association between Calliactis parasitica and Eupagurus bernhardus have been carried out.
  • 2The attachment of the anemone to the shell is achieved by a remarkable manoeuvre involving the attachment of the tentacles and oral disc, the freeing of the pedal disc and its adhesion to the shell by a somersaulting movement, with the eventual release of the oral attachment and the assumption of the normal posture on the shell.
  • 3Active participation of E. bernhardus in detaching the anemone and transplanting it on the shell was not observed, in contrast to the active parts played by the crabs Pagurus striatus and P. arrosor in their associations with C. parasitica.
  • 4C. parasitica becomes attacvhed to empty shells no less quickly or frequently than to shells occupied by E. bernhardus.
  • 5The anemone readily settles on shells of living Buccinum undatum in the laboratory and does not desert these for shells occupied by crabs. It does not settle on shells cleaned by boiling in strong alkali.
  • 6The respective roles of anemone and crab in the associations between Calliactis and these three species of pagurid crabs are discussed from the stand-points of comparative behaviour and with special reference to the capacities of the actinian neuromuscular system here displayed.

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