MARINE ANIMALS THAT SHOCK 135 



Recovery generally takes place within several days. It is believed 

 by some that the primary cause of polar bear poisoning is due to 

 Vitamin A, which is present in large concentrations in certain polar 

 bear tissues. 



Bearded Seal, Erignathus barbatus (Erxleben) (Fig. 86, Top). 

 This species is circumboreal in its distribution, living at the edge 

 of ice. The liver of this seal is said to contain a high concentration 

 of Vitamin A, and may be as toxic as polar bear liver. 



Australian Sea Lion, Neophoca cinerea (Peron) (Fig. 86, Bot- 

 tom). This sea lion is confined to the coast of South Australia. The 

 flesh of this animal is said to be toxic, but there is very little 

 supporting data upon which to base any conclusions. 



Whales and Dolphins. Several species of whales and dolphins are 

 reported to have poisonous flesh, but data is too meager at this 

 time to permit any definitive statements . 



MARINE ANIMALS THAT SHOCK 



Electric fishes constitute a relatively minor health hazard but, 

 nevertheless, they are worthy of serious consideration. There are 

 several different groups of fishes that possess electric organs : cat- 

 fishes (Malopterurus) , star-gazers (Astroscopus) , electric eels 

 (Electrophones), and a number of genera of electric rays (Tor- 

 pedo, Narcine, Hypnarce, Hypnos, Discopyge, etc.). Electric eels 

 and catfishes are freshwater inhabitants, whereas star-gazers and 

 rays are marine. The most important marine members are the 

 electric rays, representatives of which are found in all temperate 

 and tropical oceans. Electric rays are sluggish, feeble swimmers, 

 spending most of their time lying on the bottom partially buried 

 in the mud or sand, generally preferring shallow depths. 



The electric organs, which constitute about one-sixth of the total 

 body weight of the ray, are situated one on either side of the an- 

 terior part of the disc between the anterior extension of the pec- 

 toral fin and the head, extending from about the level of the eye 

 backward past the gill region. Usually, outlines of the organs are 

 externally visible on both the ventral and dorsal sides. The organs 

 are comprised of columnar prism-like structures separated by loose 

 connective tissue, forming a network similar to the cells of a honey- 

 comb. The columns vary in number according to the species of 

 ray. The ventral side of the ray is electrically negative whereas 

 the dorsal side is positive. The production of an electrical discharge 

 or shock is believed to be a simple reflex action — the result of tac- 



