Sharks 229 



Fertilization is internal. Located on the inner edges of 

 the pelvic fins of the male is a pair of organs (claspers) 

 used to introduce the sperm or sexual products of the male 

 into the two sexual openings of the female. These female 

 sexual openings are located within the one large opening 

 on the ventral surface of the body, the so-called cloacal 

 opening. Both intestinal and urinary wastes and young 

 are discharged through the cloacal opening. 



Only a few species of sharks lay eggs. In most species 

 the young are born alive. Compared with the true fishes, 

 the number of young born at any one time is small, usually 

 considerably less than 80. In the true fishes the number of 

 eggs laid may range from several hundred into the miUions. 



Sharks are mostly flesh eaters. The larger, more active 

 species may feed on other sharks, seals, and sea turtles, 

 as well as on fish. Some with crushing teeth regularly eat 

 crabs, lobsters, and shellfish. The whale shark and the 

 basking shark, two of the largest species, feed on small 

 shrimp-like animals and on small fishes. Most sharks are 

 scavengers, and they will often concentrate in areas where 

 garbage is being dumped. The sense of smell is well de- 

 veloped in sharks. Blood appears to excite them, and an 

 injured, bleeding person is more likely to be attacked by 

 some of the more aggressive species (such as the tiger, 

 white, or hammerhead sharks) than is a casual swimmer. 

 Shark attacks are most common in tropical waters and 

 are more liable to occur at night than in the day. They are 

 also more apt to happen in deep waters offshore than along 

 shallow beaches. 



Economic Importance: There is ajimited fishery for sharks 

 throughout the world in areas where they are abundant. 

 The hide is used for leather; the liver oil of some species 

 is a source of Vitamin A. The fins of certain species are 

 considered a delicacy in the Far East. Many kinds of 

 shark are regularly sold for human consumption, or are 

 processed for use as feed for poultry and livestock. 

 Classification: The scientific classification of the sharks 

 found in the area from Cape Cod to Cape Hatteras is as 

 follows : 



