48 THE SENSES OF ANIMALS 



Pansies of other colours will be taken in due course, but the 

 attraction of yellow is most marked and would seem to be 

 the colour which is seen best. 



The turtles, terrapins, and pond tortoises take their food 

 under water, and from such experiments as I have been able 

 to make it would appear hkely that colour-sight plays little 

 part in feeding behaviour, movement of the prey being the 

 main stimulus. 



From many observations on terrapins and pond tortoises 

 in captivity, I am also of the opinion that vibrations set up 

 in the water by tadpoles, worms, small fish, and some aquatic 

 insects (on which most of these reptiles feed) are a means of 

 attracting attention to the presence of food. I have frequently 

 placed an earthworm in a tank well behind and out of sight 

 of a terrapin or pond tortoise. The worm on being submerged 

 will start to move, often wriggling though remaining in the 

 same spot. As soon as this takes place the reptile will make 

 a turn or half-turn, thus bringing the worm within sight. If 

 hungry enough, the pond tortoise will at once move and 

 seize the worm. It has been argued that smell may explain 

 this behaviour, but I am inclined to think that such a quick 

 reaction to the currents set up by the movements of the worm 

 is due to a perception of water vibrations. Though I shall 

 say more about this when dealing with the sense of smell, it 

 is worth recording that I have placed dead worms into a 

 tank in order to test my theories, and I have found that the 

 time taken by a terrapin or pond tortoise to get some scent 

 from a dead worm which is out of sight is much longer than 

 that taken to detect a living worm. 



In the crocodiles and alligators it is difficult to decide 

 which sense plays the most important part, since these reptiles 

 have good powers of scent, sight and hearing. Most of the 

 food is eaten out of the water though, of course, such food 

 items as fish must be taken beneath the surface. 



The eyes are well equipped for seeing on land and beneath 

 the water, and this can be easily observed by anyone who 

 can provide suitable tanks and water temperature for the 

 keeping of young crocodiles and alligators. A word of warn- 

 ing here: young alligators up to about eighteen inches to 

 two feet in length can be tamed to some extent and will even 



