236 Nurse Shark 



Color: Upper side and back variable; brown, blue-gray, 

 dark gray or almost black. Lower sides a lighter shade of 

 back color. Lower surface mostly white, sometimes mottled 

 with gray. 



Distribution: World-wide in the subtropical zone and 

 warmer waters of the temperate zone. In the western 

 Atlantic, reported from the Gulf of St. Lawrence to north- 

 ern Argentina, with most appearances recorded off south- 

 ern New England. 



Size: May grow to over 20 feet in length. Fish 13-16 feet 

 common. A fish 13 feet long weighs about 400 pounds. 

 General Information: Usually found a few miles offshore 

 swimming near the surface. Feeds on smaller schooling 

 fishes including mackerel, bluefish, herring, bonito, and 

 menhaden. The long, whip-like tail is used to splash the 

 water to frighten the schools of fish into a concentrated 

 mass while the shark gradually swims in a narrowing 

 circle around them. Occasionally, two thresher sharks may 

 work together. Sometimes the tail is used to lash out and 

 stun the prey. 



Economic Importance: Of little importance in the com- 

 mercial fisheries. Frequently caught by sport fishermen off 

 the New York and New Jersey coasts. 



Nurse Shark 

 Ginglymostoma cirratum (Bonnaterre) 



Color: Upper surface of body yellow-brown to gray-brown. 

 Remainder of body lighter shade of same color. 

 Distribution: Found on both sides of the Atlantic and in 

 the American Pacific oceans in tropical and subtropical 

 waters. In the western Atlantic most common in the 



