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THE ANIMAL KINGDOM 



Figure 14.18. Octopus pursuing a crab, (iiuz Guio-Couitesy LIFE Magazine. 

 Copr. 1955 Time Inc.) 



topuses feed on crabs and other arthropods. They catch their prey and 

 first kill it by a poisonous secretion from the salivary glands. Then all 

 of the flesh is delicately picked out, leaving the hard parts uneaten. 

 Octopuses live among rocks, seeking shelter in small caves that they may 

 partially excavate. The motion of octopuses is incredibly fluid, with no 

 suggestion of the strength that lies in the eight arms. Their ferocity, 

 however, has been overrated. Octopuses hide during the day and come 

 out in the evening. They are by nature timid, and flee from animals as 

 large as man. The largest individuals, which may have arms 12 feet long, 

 are certainly to be respected from a distance, but these are rare. Most 

 octopuses have arms less than a foot long. 



Questions 



1. Distinguish among the five classes of molluscs. 



2. Compare the chiton with a generalized mollusc. 



3. Describe the radula. 



4. What is torsion? 



5. Give examples of gastropods that (a) swim, (b) have no shell, (c) breathe air. 



6. How does Verms feed? 



7. Describe sexual phenomena in the oyster and the squid. 



8. Why are the tentacles and siphon of the squid considered to be parts of the foot? 



9. How does the squid sucker work? 



Supplementary Reading 



Many manuals are available for the identification and study of shells (conchology). 

 MacGinitie and MacGinitie, Natural History of Marine Animals, include interesting in- 

 formation on the activities of many animals and are especially good on the molluscs. The 

 paperbound Seashores by Zim and Ingle contains many colored drawings of seashore life, 

 especially of the molluscs. 



