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Social Behaviour of Animals and Plants : Question 3
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The hermit crab, Eupagurus, shares its welk shell with a ragworm, Neris, which lives inside and a sea anemone, Calllactis, which is attached to the outside of the welk shell. The ragworm gains protection and benefits from the scraps which break off the crabs food. The sea anemone also benefits from these scraps, as well as from the crabs mobility. The crab gains protection from the sea anemones tentacles which are armed with stinging cells.


Answer the following questions using complete sentences.


(a) Are any of these three animals parasites? Give a reason for your answer.






(b) What, if any, is the relationship between the ragworm and the sea anemone? Again, give reasons for your answer.






(c) A hermit crab which has had the sea anemone removed from its shell will hunt around for a replacement. When it finds one, it uses its pincers to place the new anemone on its shell. What does this information tell you about the relationship between the sea anemone and the crab? Answer the question as fully as you can.







(d) What relationship does the ragworm, Neris, have with the hermit crab?