524 



THE COMMUNITY 



Fig. 174. Drawing of the hand of an aye-aye. 

 Note the attenuated middle finger. 



stout ant and teimite nests with their fore- 

 paws and can concentrate their insect food 

 on their long, cyUndrical tongue. 



The availability of food is also related to 

 the size of the animal. Other things being 

 equal, larger animals not only eat larger 

 pieces of food, but also quarter more ter- 



portionately large area in relation to their 

 body size. 



In a small sample of forest floor leaf 

 mold, say 2 kg. wet weight, there may be 

 10,000 herbivorous oribatid mites, 2000 

 herbivorous coUembolans, and one preda- 

 ceous pselaphid beetle. Most of these arth- 

 ropods are minute (0.5 to 1.5 mm.) at 

 maturity, but cover different amounts of 

 territory at different speeds. Whereas the 

 mites must crawl, most of the coUembolans 

 can leap, and the beetle can crawl or fly. 



Reproduction also influences range and 

 is indirectly a factor in the size and shape 

 of the pyramid of numbers. Every nonpar- 

 thenogenetic female must be near enough 

 to a male to ensure fertiUzation within his 

 and her Ufe span, if they are to be instru- 

 ments in perpetuation of the species. Par- 

 thenogenetic species are not so restricted, 

 but even these usually require fertiHzation 

 of their ova at the approach of adverse 

 physical conditions. This is common in roti- 



Fig. 175. The paddlefish (Polyodon spathula) feeding on daphnids. (Courtesy of the John 



G. Shedd Aquarium.) 



ritory to find it. Thus a grizzly bear may 

 range over 40 square miles, a red squirrel 

 over 5 acres, a vole over 1000 square feet, 

 and a leaf mold mite over a few square 

 inches. 



Range, then, indirectly affects the pyra- 

 mid of numbers, and territory is partially 

 affected by method of locomotion. Volant 

 animals, such as birds, may cover a dispro- 



fers and aphids (p. 275) and has been 

 carefully analysed for cladocerans by Banta 

 (1939). 



There are numerous exceptions to the 

 size/numbers ratio of the food web. Most 

 are apparent rather than real. 



For example, the whale-bone whales and 

 the paddlefish (Polyodon spathula) are dis- 

 proportionately large in relation to the size 



