THE LOWER FISHES 147 



All of the gill slits are anterior to the pectoral fin. There is only one genus in 

 the family- The species are ovoviviparous and are cosmopolitan in warm waters. 



SAND SHARK (sAND TIGER ) : Carcharias taurus 



Size: Averages 4 to 6 feet. Up to 9 feet. 



Weight: Up to 250 pounds. 



Distribution: Maine to Brazil. Most common in warm temperate waters and 

 rare in the tropics. 



Identification: Grayish brown above, fading to white below. The young have 

 light spots and blotches which disappear with age. 



Habits: This is the most common large shark swimming over sandy beaches. 

 It is fairly sluggish but can move at good speed when the occasion demands. 

 It feeds principally at night on fishes and squids and occasional large crustaceans, 

 the sharp, pointed teeth serving admirably to hold such slippery prey. They 

 may feed in large schools in very shallow water. Although there are no records 

 of attacks on man, this shark is to be respected. 



MACKEREL SHARKS: Family Isuridae 



These are unquestionably the most active, swiftest, and most voracious of 

 sharks. The modifications toward swiftness are good field marks. These are 

 (1) a compact and torpedo-shaped body, (2) a high first dorsal fin placed at 

 the highest point on the back, (3) reduced second dorsal and anal fins of 

 nearly equal size, (4) a narrow caudal peduncle reinforced with lateral keels, 

 and (5) a lunate tail in which the lobes are of nearly equal size. In many of 

 these respects, they resemble the mackerels and spearfishes which are among 

 the very swiftest of bony fishes. The gill slits are anterior to the pectoral fin. 

 There is no spiracle. 



The coloration is characteristic and like that of most pelagic fishes being a 

 sea-blue above and white beneath, an example of obliterative coloration 

 (Chapter 2). 



These are primarily fish-eaters and are found in all temperate and tropical 

 seas. They are ovoviviparous. 



MAKO (sharp-nosed MACKEREL shark) : Isurus oxyrhincus 



.Size: Averages 6 feet. Up to 12 feet and possibly a little larger. 



Weight: Averages 150 pounds. Up to 1,200 pounds or more. 



Distribution: Tropical and warm temperate Atlantic. Common in the Bahamas. 

 In summer to New England. 



Identification: Anal slightly posterior to second dorsal. Coloration is slate-blue 

 above, abruptly changing to dirty white below. The snout is conical and sharply 

 pointed. The teeth are slender and recurved for holding fish. 



Habits: This may be the swiftest shark that swims. It is pelagic and pursues 

 swift, schooling fish such as mackerel and herring for food. Occas'onal squids and 

 sea turtles are taken. This fish is best known for its habit of leaping spectacularly 

 from the water especially when hooked, but it is most often seen basking at 

 the ocean's surface, solitary or in small schools, with the large dorsal fin pro- 

 truding. It can be dangerous, particularly around boats. It's near relative, the 

 bonito shark of the Pacific, Isurus glaucus, has been known to attack men and 



