THE SQUID 39 



XII. THE SQUID 

 Materials. Specimens of squid. 



Directions. (The squid is a marine mollusk. It is common 

 along the shores of the United States, and may be obtained from 

 any of the dealers in zoological supplies. A half dozen or so should 

 be in the collection for comparison with the clam and other mol- 

 lusks.) 



Note the long, cylindrical body, with a distinct head. 

 Does it possess a shell like the clam or oyster ? Imbedded 

 in the thick mantle straight down the back is a rudimentary 

 shell known as the pen. Did the clam possess a distinct 

 head? Note on the head of the squid the long arms, or 

 tentacles. How many pairs are there? Note that one 

 pair is longer than the other pairs. Note the sucker disks 

 on the inside of the short arms. Note that the long arms 

 do not bear the suckers the whole length, but only on an 

 expanded portion near the end. How many rows of the 

 cuplike suckers on this expanded portion? Are they all 

 of the same size ? Note in the middle of the cluster of arms, 

 at their bases, the mouth. Note the black, horny beak, 

 something like the beak of a parrot. 



How many eyes has the squid ? Where are they ? Did 

 the clam have eyes? At the posterior part of the body, 

 note the triangular flaps of skin. These are the so-called 

 fins. They are used to guide the animal in swimming. 



Make a drawing of the dorsal side of the animal. 



Beneath the skin of the body are numerous pigment 

 cells. They appear like freckles all over the dorsal side 

 and are usually purplish in color. These cells can be ex- 

 panded until they touch one another or suddenly contracted 



