where they take a yearly toll in injured 

 bathers. Some skates are found off the 

 coasts of the northern European coun- 

 tries in sufficient abundance to support 

 small but continuous foodfish fisheries. 



The larger skates and rays are ap- 

 parently less numerous, but our knowl- 

 edge of their abundance is based, for 

 the most part, on incidental sightings 

 of these creatures from coastwise 

 vessels. Claims of great local abun- 

 dance of eagle rays, mantas, and simi- 

 lar fish are often based more on the 

 great amount of publicity given a few 

 sightings than on actual numbers. 



Size 



The mantas, reputed to reach a 

 breadth of 2Z feet and a weight of over 

 3,000 pounds, are the largest fish of the 

 group. Sawfishes are also quite large 

 and may reach a total length of 22 feet, 

 although actual verified records do not 

 exist for specimens this large (see 

 table on the inside cover). At the other 

 end of the range there are a few species 

 of ray and torpedoes that never exceed 

 a few inches in breadth. 



Food and Feeding Habits 



Most skates, rays, and closely re- 

 lated forms are bottom feeders, and 

 crabs, shrimp, other crustaceans, 

 clams, and worms constitute their 

 principal food items. Many skates cap- 

 ture prey by swimming quickly above 

 the victim, dropping down on it, and 

 preventing its escape by covering it 

 with their winglike fins. Some of the 

 more sluggish rays appear to lie in 

 wait for their prey- -half covered with 

 sand, and many of the members of the 

 group seem to prefer to feed only at 

 night. 



Sa'wfish feed primarily on and in the 

 bottom, which they scrape and dig up 

 with their saws, but they also feed in 

 open water, where they capture their 

 prey by slashing their sa'ws around in 

 the midst of schools of fish. 



A few rays- -principally the devil 

 rays and mantas- -feed on pelagic 

 shrimps, mysids, and small school 



fish. On rare occasions the devil rays 

 appear to scoop up their prey with the 

 help of the cephalic extensions of their 

 pectoral fins, and folk legend, ap- 

 parently based on fact, states that they 

 will even wrap their wings around 

 anchor cables. 



The electric rays and torpedoes 

 possess the structural organization and 

 the ability to transmit an electrical 

 shock. The mechanism by which this is 

 achieved is not completely known. It 

 appears to involve an increase in 

 activity of the nerve-muscle complex, 

 common to all animals. Release of a 

 demonstrable electric discharge is a 

 heightened example of a prevalent phe- 

 nomenon. A nervous response involves 

 an electrical impulse traveling along a 

 pair of nerve fibers and acting upon 

 a section of the brain (at one end of the 

 circuit) and a muscle (at the other end). 

 The "electric organ" of torpedoes is a 

 wing- shaped mass of modified muscle 

 tissue, richly innervated, lying in the 

 forepart of the body on either side of 

 the vertebral column. A so-called 

 "electric lobe" in the brain completes 

 the nerve pathway. Textbooks of com- 

 parative or general physiology may be 

 consulted for further particulars. 



The Atlantic torpedo, a relatively 

 large ray which reaches a length of 

 nearly 6 feet and may occasionally 

 weigh as much as 100 pounds, is said 

 to have produced a discharge amounting 

 to 220 volts. This is probably very 

 nearly the maximum discharge to be 

 expected from a ray and is much less 

 than the maximum reported for electric 

 eels. Very little is known about the 

 discharges of other electric rays and 

 torpedoes, except that the discharges 

 of the electric ray are pulsed and de- 

 livered in rapid succession--very simi- 

 lar, in principle, to the mechanism used 

 in present-day applications of elec- 

 tricity in commercial fishing. Exami- 

 nation of stomach contents of a number 

 of electric rays and torpedoes suggests 

 that the discharges are used in food 

 getting, for the size of many of the 

 fishes found in stomachs is larger than 

 would be expected on the basis of more 

 ordinary means of capture. 



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