BUSYCON, LOLIGO 153 



CEPHALOPODA 

 LOLIGO PEALEI (The Squid) 



Specimens of this or closely related species are rather 

 common along the Atlantic coast of the United States. They 

 are active swimmers, but may occasionally be seen in shallow, 

 quiet water near the shore. The movements and positions of 

 adult specimens in aquaria should be studied. Do you know 

 what they eat and how they capture their food? 



Study a small living specimen in a jar of sea water and 

 notice: 



1. Its general shape and distinct head. 



2. Its position in the water. For convenience, the lower 

 surface may be referred to as ventral, but this is not to be 

 considered as morphologically the same as the ventral surface 

 of other Mollusca. What parts are kept moving? Why is 

 water pumped when the animal is not swimming? 



3. In what direction can it swim best? Can it swim in the 

 other direction? How does it swim? Is the funnel movable? 

 How does it guide its movements? 



4. Its color. Irritate it and see what happens. What pur- 

 pose does the change in color serve? What is the ink for? 



5. What happens when the end of a finger is placed within 

 the circlet of tentacles of an animal about two inches long 

 that is being held firmly? 



Using an adult specimen, observe: 



1. The arrangement of the arms on the head. Are they 

 arranged in any definite order? Are they all alike? 



2. The suckers of the arms. Do they follow the same 

 order on all of the arms? 



3. The structure of a sucker. " Notice the peduncle, outer 

 thin margin, horny ring, and piston. Is the horny ring 

 smooth? What is its function? How does the sucker work? 

 Split one and draw the cut surface. 



4. The mouth. Where is it placed? Notice the tips of the 

 horny beak. Which jaw is the longest? 



5. The eyes. 



