CHAPTER III 



ENEMIES OF THE MOLLUSC A MEANS OF DEFENCE — MIMICKY AND 



PROTECTIVE COLORATION PARASITIC MOLLUSCA COMMEN- 



SALISM VARIATION. 



Enemies of the MoUusca 



The juicy flesh and defenceless condition of many of the Mollusca 

 make them the favourite food and often the easy prey of a host of 

 enemies besides man. Grulls are especially partial to bivalves, and 

 may be noticed, in our large sandy bays at the recess of the tide, 

 busily devouring Tellina, Mactra, My a, Syndosmya, and Solen. On 

 the Irish coast near Drogheda a herring gull has been observed ^ 

 to take a large mussel, fly up with it in the air over some shingly 

 ground and let it fall. On alighting and finding that the shell 

 was unbroken it again took it up and repeated the process a 

 number of times, flying higher and higher with it until the shell 

 was broken. Hooded crows, after many unavailing attempts to 

 break open mussels with their beak, have been seen to behave 

 in a similar way.^ Crows, vultures, and aquatic birds carry 

 thousands of mussels, etc., up to the top of the mountains above 

 Cape Town, where their empty shells lie in enormous heaps 

 about the cliffs.^' 



The common limpet is the favourite food of the oyster- 

 catcher, whose strong biU, with its flattened end, is admirably 

 calculated to dislodge the limpet from its seat on the rock. 

 When the limpet is young, the bird swallows shell and all, and 

 it has been calculated that a single flock of oyster -catchers, 

 frequenting a small Scotch loch, must consume hundreds of 



1 W. V. Legge, Zoologist, 1866, p. 190. - Blackball, Researches, p. 139 



* Barrow, Travels in South Africa, ii. p. 67. 



