144 UNDERWATER GUIDE TO MARINE LIFE 



PORT JACKSON SHARK (horned shark) : Heterodontus francisci 



Size: Up to 4 feet. 



Distrihtition: Point Conception to the Gulf of California. 



Identification: Same as for the family. 



Habits: This is a fairly common shark living near kelp in shallow or deep 

 water. It keeps to the bottom and eats hard-shelled invertebrates which it 

 crushes with its strong molar teeth. The large and unmistakable eggs may 

 sometimes be found wedged in among rocks near the low tide zone. 



The Modern Sharks 



These sharks are divided into three large groups. The rays are derived from 

 them. 



Notidanoids: Superfamily Notidanoidea 



These most primitive of modern sharks comprise a rare and poorly known 

 group. They reach large size and are mostly in moderately deep water of 100 to 

 400 fathoms, only occasionally coming within the depth range of the diver. 

 The single dorsal fin, long, cylindrical body, and the presence of six to seven 

 gill slits are good field marks. They are widespread in the temperate and tropical 

 waters of the world. 



COMB-TOOTHED OR COW SHARKS: Family Hexanchidae 



The teeth of these sharks are unique, being completely unlike in the two 

 jaws. These large sharks are found in all warm oceans but are not common, 

 it appears. They are ovoviviparous. Identification is made easy by the presence 

 of but one dorsal fin. 



TEETH x^ ^^S-50. Cow shark. 



cow SHARK (six-GiLLED SHARK, GRisET, MUD shark) : Hexanchiis griseus 



Size: Up to 15 feet, exceptionally to 26 feet. Matures at 6 feet. 



Weight: Up to 1,300 pounds. 



Distribution: All warm seas. In the Atlantic from Cape Hatteras to the 

 Caribbean. In the Pacific from southern California to British Columbia. Not 

 rare in Cuban waters and off San Diego. 



Identification: Dark brown or gray with a light streak along the lateral line. 

 There are six gill slits. 



