ANIMALS THAT LIVE WITHOUT WATER 1/3 



organ has this function in the green turtle (Chelonia 

 mydas), the salt-water crocodile, in several sea-snakes 

 (the gland seems to be absent in one sea-snake, 

 Pelamis), and the marine iguana. Only in the iguana, 

 however, is the drinking of sea water perhaps habitual 

 because of the animal's diet of seaweed. 



The allusions in Carroll's Alice in Wonderland: 'So 

 they went up to the Mock Turtle, who looked at them 

 with large eyes full of tears'; and again in Kipling's Just 

 So Stories: 'for I am the Crocodile, and he wept croco- 

 dile-tears to show it was quite true,' and elsewhere to a 

 propensity for tear production in reptiles failed to stir the 

 scientific imagination, Schmidt-Nielsen and Fange note, 

 and consequently an important chapter in the regula- 

 tion of the composition and volimie of the body fluids 

 has long been neglected. Probably neither Carroll nor 

 Kipling ever saw a marine turtle or crocodile cry. and if 

 they had they could not have known how salty the tears 

 would be. But the phenomenon was possibly well known 

 to seafaring men of their day, an incredible strand of 

 verity entangled in unreliable legend— for even in Car- 

 roll's day, mock-turtle soup was made with calf s head, 

 veal or other meat. 



With the possible exception of the iguana, the salt 

 gland in the marine reptiles, as in the birds, probably 

 serves as a safety device, protecting against excessive in- 

 gestion of salt or loss of water. No such organ is present 

 in the marine seals or whales, which by present evi- 

 dences must rely on the kidney for body fluid regulation. 

 The discovery of the salt gland in the marine reptiles 

 will perhaps send the paleontologist scurrying back to 

 the fossil record because it may be possible to judge the 

 relative size of the gland in better preserved skulls and 

 to determine if this imique adaptation aided the Tri- 

 assic and Jurassic ichthyosaurs and plesiosaurs and the 

 Cretaceous mosasaurs to establish themselves in a marine 

 habitat. 



