THE HUNTING SPIDERS 207 



by clinging to underwater leaves and stems bobbing up to the 

 surface like corks when they release their hold. 



The aquatic pisaurids are able to remain beneath the water for 

 long periods. One instance of forty-five minutes has been noted, 

 and the limit is probably much longer. The body hairs capture 

 bubbles of air, thus making the spiders even lighter; and although 

 this further impairs their swimming abilities, some of the bubbles 

 come in contact with the respiratory orifices and furnish the needed 

 oxygen for their underwater sallies. 



About a dozen species of Dolomedes are known from the United 

 States, and some of them vie with the giant wolf spiders for the 

 honor of being our biggest true spiders. Perhaps the largest is a 

 robust fisher spider covered with dark brown hairs mottled by lines 

 and spots of grayish and yellowish hairs, Dolomedes okefenokensis, 

 first discovered in the Okefenokee Swamp in Georgia. The females 

 often attain a body length of more than an inch and a half, and 

 their lightly ringed legs span four or five inches. The male is 

 considerably smaller than his mate and somewhat more brightly 

 colored, the pattern of dark spots and pale lines usually being quite 

 distinct. Similar species occur commonly in the northern states, 

 and, even though of smaller size, seem formidable enough when 

 happened upon along beaches or in boathouses. The sluggish 

 streams and marshes of the United States, particularly those of our 

 southeastern states, harbor many species of these vigorous creatures. 

 Dolomedes albineus, an ash-gray spider of average size, is a con- 

 firmed aquatic type and deserves special mention. It rests with legs 

 outspread and head downward on the trunks of cypress and tupelo 

 trees in the southern swamplands, completely motionless until dis- 

 turbed, when it whisks out of sight around the tree trunk like a 

 squirrel, or dashes into the water to skate away or hide under the 

 surface. 



Brief mention should be made at this point of the species of 

 Trechalea, a group of large American fishers similar to Dolomedes, 

 of which a single representative extends its northern range into the 

 high mountains of Arizona. Trechalea flattens its grayish, black- 

 flecked body against a stone at the edge or in the water of streams, 

 poised to skate out at the first sign of a struggling insect. The 

 activities of this creature mark it as one of our finest fishers, an 

 expert with unusually good eyesight, and tarsi that are very long 

 and flexible to aid in water walking. 



Most handsome of all American fisher spiders is Dolomedes 



