4 AMERICAN SPIDERS 



sight of all spiders, they emulate the carnivores in stalking their 

 prey. Their stout bodies and legs are gaily colored and bedecked 

 with tufts of bright hairs, pendant scales, and curious spines. Gleam- 

 ing with their iridescent scales like jewels in the sun, they rival the 

 gaudiest insects. During courtship dances, the little males caper and 

 posture before the females in such manner as to display their bril- 

 liant ornaments to best advantage. 



In the petals of many kinds of flowers hide stubby little crab 

 spiders which, simulating the assasin bugs, seize flying insects that 

 visit the blossoms for nectar. In keeping with their role of decep- 

 tion, they change from white to yellow, or vice versa, to conform 

 with their background. 



All spiders breathe air through orifices on the ventral side of 

 the abdomen. In spite of their air requirements, many have adopted 

 an amphibious life and stay under water for periods of variable 

 length. Some live in little waterproof chambers spun in holes in 

 coral rock that are covered over during high tide. Most extraordi- 

 nary of all is the water spider, Argyroneta of Eurasia, which is able 

 to swim about and live for weeks in the fresh water of streams and 

 ponds in a domicile that resembles a small diving bell. This spider 

 carries air bubbles beneath the surface to its retreat, which is an- 

 chored to aquatic plants by silk lines, and keeps a supply of air 

 imprisoned in the silken chamber. Its prey consists of small aquatic 

 animals, which it captures in the stream. Even the eggs are laid and 

 the family hatched out under water in the security of the nest. 

 Among American amphibious spiders are some of the fisher and 

 wolf spiders, which run over the surface freely and dive into its 

 depths where they stay for long periods. Occasionally small fish or 

 amphibians are caught by the large fisher spiders of the genus Dolo- 

 medes. 



The sexual characteristics of spiders are especially interesting. 

 In both sexes the genital opening is a simple pore beneath the base 

 of the abdomen through which emerge the spermatozoa or eggs. 

 One would expect that during mating the male products would be 

 transferred directly to the female by contact between these orifices 

 or by means of an eversible intromittent organ. Instead, the male 

 spider has transformed the claws on the ends of the pedipalpi (the 

 leglike appendages lying on each side of the head in both sexes), 

 into a complicated intromittent organ, comparable to a syringe or 

 a hypodermic needle, and has modified and greatly enlarged the 

 distal segments of the pedipalp to protect the organ and facilitate 



