292 



Shark and Compafiy 



Frilled shark {Chlamydoselachus anguineus). 



Courtesy, American Museum of Natural History 



California. A deep-water shark which feeds on squid and octopus, 

 the Frilled shark is ovoviviparous. The gestation of its young has been 

 estimated to be as long as 2 years. The largest known specimen was 

 nearly 6^ feet long. 



Family Hexanchidae—Six-G\i.i.^Y) Sharks and 

 Seven-Gilled Sharks 



Like the Frilled shark, these sharks are primitive creatures. Their 

 long, slim bodies still display vestiges of some features of most ancient 

 species: six or seven gill slits— and a single dorsal fin. Of the many known 

 species of sharks in the sea today, none resembles its primeval ancestors 

 more than the Hexanchidae. Fossil remains of a shark almost identical 

 to the Seven-Gilled have been recorded from the Jurassic Period, 

 which means they last swam the seas about 150 million years ago, accord- 

 ing to our current estimates of geological time. 



The only known species of Six-Gilled shark (Hexanchus griseus 

 Bonnaterre, 1780) is found throughout the world— in continental waters 

 of both the eastern and the western Atlantic; the Mediterranean; the 

 North American Pacific coast from northern British Columbia to 

 southern California, and along the Chilean coast. It is also found in the 

 waters of Japan and in the Indian Ocean. 



Six-gilled shark ( Hexanchus griseus ] 



Courtesy, Fisheries Research Board of Canada 



