Selachians Extraordinary 247 



techniques of survival. Always, however, they have remained Selachians. 

 They are basically nothing more than flattened sharks. They breed 

 like sharks, feed carnivorously like sharks, and, in their very skeletons, 

 they carry the gristly substance which separates all sharkdom from the 

 bony fishes: cartilage. 



Alost Batoids are sluggish bottom-dwellers, for their flattened bodies 

 were developed for life on or near the ocean floor. (But not all. Certain 

 huge pelagic species have been encountered in the Pacific and the Indian 

 Oceans about which, unHke the Atlantic A4antas, we know little or 

 nothing.) Since most of them have found their destiny on the ocean 

 bottom, they have had to adapt their breathing to their environment. If 

 they inhaled water while they rested on the bottom, they might scoop 

 in sand which would injure the delicate gill-filaments within their un- 

 derside gill slits. So they breathe in reverse, drawing in water through 

 their spiracles. The spiracle, on the top side of the body, is equipped 

 with a valve, and the water is drawn in, then expelled through the gill 

 clefts on the underside. If a foreign object such as sand or a bit of sea- 

 weed is introduced in the spiracle, the bottom-dwelling Batoid has an- 

 other trick up its spiracle— it spouts water and drives out the obstruction. 



Batoids range in size from small rays only a few inches across to the 

 huge Giant Devil ray (Ma?7ta birostris), known to grow to a breadth of 

 22 feet or more and a weight of more than 3,000 pounds. 



No known Batoid has the sharp-pointed teeth found in many sharks 

 Batoids' teeth vary from thorn-like prongs on a broad base to rounded 

 or plate-like, and they are usually arranged in bands or a kind of mosaic 

 that sometimes resembles paving stones. This type of dentition is highly 

 efficient for crushing the moUusks and crustaceans that are usually found 

 in the bottom-dwelling Batoid's diet. 



Let us now take a closer and more systematic look at the Batoids. 

 First, the Electric Rays. 



Family Torpedijiidae— Electric Rays 

 Set apart from all other ray families is that of the Torpedi?iidae—the 

 Electric rays— which encompasses more than 30 species. Electric rays of 

 various types are found in all the oceans of the world. 



Electric rays so fascinated the ancients that the humble fish found 

 its way into Etruscan vases, Roman mosaics, Egyptian murals, and 

 Greek literature. 



Our word narcotic comes from the Greek word for the Electric ray, 

 narke. The Greeks believed that the "Numbfish" could bewitch both 

 its prey and the fisherman angling for it. Because Socrates similarly be- 

 witched—or perhaps numbed— his listeners with spellbinding oratory, 

 he was compared by his colleagues to the Numbfish. And the ancient 



