APLYSIA. 191 



FOOD. 



The food of Aplysia consists of seaweeds of various kinds. 

 When full grown it lives on green and brown weeds such as 

 Viva lactuca, species of Fucus, etc., and the colour and markings 

 of its skin bear a close resemblance to the weed (vide External 

 Characters). The animal can adapt itself to its surroundings, 

 and undergoes remarkable colour changes which very quickly 

 enable it to imitate the particular weed on which it is feeding 

 at the time. Thus very small specimens feed on red weed 

 like Delesseria and are coloured rosy red', larger specimens 

 feeding on weed from the Laminar ia zone are brown, while those 

 feeding on Fucus are olive brown. (Vide Life History.) 



If the contents of the crop be examined, Foraminifera, 

 little Ophiuroids, and small Gastropods may sometimes be 

 found, but these have probably been consumed accidentally 

 along with the weed and do not form the bulk of the food as 

 Cuvier implied in his account of the Sea-hare.* 



LIFE-HISTORY. 



During the spring the Aplysiae come up into shallow 

 waters to deposit their cordons of eggs amongst the weeds 

 between tide marks. From the eggs hatch, in about a fort- 

 night, free-swimming veliger larvae, which lead a pelagic 

 existence. The metamorphosis into the adult form is not 

 known. The youngest Aplysiae found are about a quarter 

 of an inch in length, and are brought up in the dredge attached 

 to red weed. These young forms are of a deep rose-red colour 

 and feed upon the weeds which they so closely resemble. 

 Apart from the differences in the shape of the tentacles they 

 are in external form like the adult, though differing from them 

 so markedly in colour. These small red specimens were 



* Cuvier, G. " Memoires pour servir a l'histoire et a 'anatomie des 

 Mollusques." Paris, 1817. 



