Selachians Extraordinary 245 



Navy entered a bathyscaphe and dived to 2V2 miles. There, where the 

 water pressure has a crushing force of 5,900 pounds per square inch, 

 and where darkness is complete and eternal, a 6V2-foot shark glided 

 through the beam of the bathyscaphe's light and looked at it with great 

 protruding eves. "Every time we have visited the bottom wastes in the 

 bathyscaphe," Houot later reported, "we have seen at least one shark. 

 Unless our luck has been phenomenal, this must mean there are thousands 

 of them living in the world's dark basement." 



About 150 species of sharks, skates, and rays are found in North 

 American waters. Many species range far beyond the arbitrary boun- 

 daries set up for them by ichthyologists. Facts about Selachians are 

 evasive, especially facts about where they may be found. In our Se- 

 lachian biographies, we have tried to list the likeliest whereabouts of 

 each. But, lured by a fleeing school of fish, or an errant oceanic current, 

 or an unusual fluctuation of temperature, members of any species can 

 stray far outside their normal home waters. 



Many species are known by several names. One man's Sand shark 

 is another man's dogfish, and one man's ray is another man's skate. There 

 are quite different sharks that are known by identical names in different 

 places. The scientific name of a species must be the only dependable 

 label. Often, though, more than one scientific name has been applied to 

 a species through the years, and the attempt to end the confusion scien- 

 tifically has only added to it. However, one scientific name usually is 

 satisfactory for scientists to identify each species. We have used those 

 that are generally accepted for each species introduced. 



No common shark, skate, or ray is generally known by its awkward 

 scientific name, but only those less or little known. A common name 

 evolves, and it sticks, usually because it is sharply descriptive— as Ham- 

 merhead is to Europeans and Americans. Less common names persist, 

 however, and we have also listed many of them, probably at a certain 

 peril. For these are aliases, and, like all aliases, they becloud identity. 

 We have adopted, in fact, the standard police usage for aliases— a/.y<? 

 kjwirti as— when we list them. 



THE BATOIDS 



A creature shaped like a guitar . . . another that wields a slashing 

 saw for a snout . . . another with electric-shock power as legendary 

 as it is painfully real . . . another with a tail barb that can wound or 

 even kill . . . another that soars up from the sea and hurtles down 

 again with a crash made thunderous by an awesome, bat-shaped body 

 that weighs thousands of pounds. These are some of the Batoids, less- 

 recognized relatives of the well-known sharks. 



These relatively younger members of the Selachian family are skates. 



