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MADRAS FISHERIES BULLETIN 



VOL. XIV, 



have the power of stinging exactly like their relatives, the jelly- 

 fishes, and by carrying about this partner, the crab provides itself 

 with a whole series of ready-made batteries of stinging cells, 

 enough to frighten away any small fish looking round for a tasty 

 bonne-bouche of crab. The anemone gains also by this association 



Fig. 24. — DoriJ>pe dorsipts^ carrying an anemone seated upon a shell. 



for when the crab finds something to eat, in tearing it to pieces 

 some shreds must float within reach of the anemone's tentacles and 

 so provide it with food. Such partnerships for mutual benefit in the 

 struggle for existence are said to be instances of commensalism — 

 a subject of constant interest to the marine naturalist, so common 

 and protean is the habit. 



At the edge of the tide, the pretty yellow-legged Matuta victrix 

 is often to be seen. Its carapace is remarkable for the great purple- 

 tipped spine that stands out threateningly on either side. While 

 the general tinge is yellow, a great amount of pretty purplish 

 colouring, composed of innumerable tiny dots, is spread over the 

 carapace and the legs. 



Hermit or Soldier crabs (Tam. Sangii iiandii) inhabiting any 

 empty shells big enough for them to stow their soft tails inside, 

 are often shown. In many cases a sea-anemone has settled on the 

 shell, affording the hermit crab some protection, by reason of its 

 sting-beset tentacles, against fish enemies, and at the same time 

 profiting itself from scraps of food that float to it when the hermit 

 is making a meal. This is another good instance of the habit of 

 commensalism. 



