Fishes of the Western North Atlantic 85 



stomachs of Torpedoes. On the other hand, it has been noted that small fishes (Gobies) 

 and invertebrates placed on the head and fins of a large Australian species, Hypnos 

 monopterygium (Shaw and Nodder) 1795, which is capable of delivering a shock of 

 considerable intensity, "seemed to suffer no ill effects, though they must have received 

 shocks." 2* Even if some species of Torpedo Rays do numb their prey to some extent 

 by electric discharges, it is not likely that they are limited in their feeding to victims 

 that have been partially incapacitated in this way, for at least some fishes are so resistant 

 to currents passing through sea water that the Ray would actually have to come in 

 contact with them for its discharges to have any disabling effect. Invertebrates, it seems, 

 are more susceptible to the effect of the discharge. 



Size. The largest members of the genus Torpedo grow to a length of five or six 

 feet and, according to reports, may reach a weight of 200 pounds (p. loi); the blind 

 genus Typhlonarke (p. 80) probably reaches a length of at least four feet. At the op- 

 posite extreme, the greatest length attained by some members of the genus Narke may 

 be less than one foot. 



Development. They are ovoviviparous ; the European Torpedo marmorata is one of 

 the Rays on which the development of the pectorals (leading to their attachment to the 

 sides of the head) has been traced (p. 10 1). 2* 



Habits. The Electric Rays prey more or less indiscriminately on various crustaceans, 

 mollusks, worms, and other invertebrates, as well as fishes (p. 102), some of the latter 

 so large that it is a puzzle how the Rays manage to swallow them. A specimen of the 

 Mediterranean Torpedo marmorata^ lying o" the sand in an aquarium, has been seen to 

 raise the front of its disc while keeping the margins pressed down, thus forming a 

 cavity into which small fish were swept by the inrush of water. In one instance a small 

 shark emerged again undamaged, but in another a mullet was not seen again, probably 

 having been captured." 



Sluggish in habit and feeble swimmers, they lie on the bottom most of the time, 

 partially buried in sand or mud. The group as a whole covers a wide bathymetric range, 

 for while most of its members occur in rather shallow water and some even survive 

 stranding for some hours in the intertidal zone,^* others (genus Benthohatis) are confined 

 to at least moderately great depths (p. 127). 



Range. The geographic range of one Electric Ray or another extends to all the 

 oceans, including the Mediterranean, and covers the temperate, subtropical, and 

 tropical belts. In the Atlantic they occur northward regularly to southern New Eng- 

 land in the west and to northern Scotland (Moray Firth and Wick Bay) in the east, 

 southward to southern Argentina in the west,-^ and to the southern extremity of the 



25. Whidey, Fish. Aust., i, 1940: 165. 



26. For illustrations of successive stages in the embryonic development of the European Torpedo marmorata, see especially 

 Fritsch (Elektr. Fische, 2, 1890: pi. 15, figs. 38-43) and Garman (Mem. Harv. Mus. comp. Zool., j6, 1913: pi. 61, 

 figs. 1-3). 27. Schonlein, Z.Biol., 3/ (N. S. jj), 1895: 453. 



28. The Australian genus Hypnos has this ability (Whitley, Fish. Aust., j, 1941: 166), although its vertical range also 

 extends down to at least 120 fathoms. 



29. The most southerly record of any Electric Ray on the Argentine Coast with which we are acquainted is from Lat. 

 46° 18' S (Norman, 'Discovery' Rep., 16, 1937: 11, 12). 



