MIMICRY 



69 



Strombus mauritianus 

 Lam., which mimics Conus in 

 shape. B, Conus janus Hwass, 

 Mauritius. 



ble that the Actinian mimics the nudibranch than vice versd, 

 since Aeolis is known to be unpalatable to fishes. 



Certain species of Strombus {mauritianus L., luJiuanus L.) 

 show a remarkable similarity in the 

 shape of the shell to that of Conus, 

 so much so, that a tiro would be 

 sure to mistake them, at first sight, 

 for Cones. In the case of S. luJi- 

 uanus at least, this similarity is 

 increased by the possession of a 

 remarkably stout brown epidermis. 

 Now Conus is a flesh-eating genus, 

 armed with very powerful teeth 

 which are capable of inflicting even 

 on man a poisonous and sometimes 

 fatal wound (see p. QQ'). Strombus, 

 on the other hand, is probably fru- 



givorous, and is furnished with weak and inoffensive teeth. It 

 is possible that this resemblance is a case of 'mimicry.' It is 

 quite conceivable that powerful fishes which would swallow a 

 Strombus whole and not suffer for it, might acquire a distaste for 

 a Cone, which was capable of lacerating their insides after being 

 swallowed. And therefore the more like a Cone the Strombus 

 became, the better chance it would have of being passed over as 

 an ineligible article of food. 



Protective coloration is not uncommon among the MoUusca. 

 Littorina obtusata is habitually found, on our own coasts, on 

 Fucus vesiculosus, the air-bladders of which it closely resembles 

 in colour and shape. Littorina pagodus, a large and showy 

 species, resembles so closely the spongy crumbling rocks of 

 Timor, on which it lives, that it can hardly be discerned a pace 

 off. Helcion pellucidum, the common British 'blue limpet,' lives, 

 when young, almost exclusively on the iridescent leaves of the 

 great Laminariae, with the hues of which its own conspicuous 

 blue lines harmonise exactly. In mature life, when the Helcion 

 invariably transfers its place of abode to the lower parts of the 

 stalk and finally to the root of the Laminaria, which are quite 

 destitute of iridescence, these blue lines disappear or become 

 much less marked. 



The specimens of Purpura lapillus which occur at Newquay 



