402 



PHYLUM MOLLUSC A. 



Third Type of MOLLUSCA. The Common Cuttlefish 

 (Sepia offitinalis\ one of the Dibranchiate Cephalopods 



Habits. This common cuttlefish is widely distributed, 

 especially in warmer seas like the Mediterranean. Unlike 

 Octopus^ which usually lurks passively, Sepia is an active 

 swimmer; it moves head foremost by working the fins 

 which fringe the body, or it jerks itself energetically back- 

 wards by the outgush of water through the funnel. It likes 

 the light, and is sometimes attracted by lanterns. The 

 beautiful colours change according to external conditions 

 and internal emotions; and a plentiful discharge of ink 



FIG. 216. Side view of Sepia. After Jatta. 



often covers its retreat from an enemy. Its food includes 

 fish, other molluscs, and crabs. In spring the female 

 attaches her encapsuled eggs to seaweeds and other 

 objects, and often comes fatally near the shore in so doing. 

 The cuttles are caught for food and bait. The "cuttle 

 bone" and the pigment of the ink-bag are sometimes 

 utilised by man. 



External appearance. A large Sepia measures about 

 10 in. in length and 4 to 5 in breadth; the body, fringed 

 by a fin, is shaped like a shield, the broad end of which 

 bears a narrowed head, with eight short and two long 

 sucker-bearing arms. Besides the diffuse pigment cells, 

 there are bands across the "back." The large eyes, the 

 parrot-beak-like jaws protruding from the mouth, the spout- 

 like funnel on the neck, and the mantle cavity, are con- 

 spicuous. Beside the eyes are the small olfactory pits ; 



