75 

 Scott: Aquatic Collembola 



aquatic types with which wo are concerned here 

 require special environmental conditions. Standing 

 water generally is a preferred habitat though not 

 always a necessary condition. Collembola are not 

 "aquatic" in the true sense of the word, that is, they 

 may food and live primarily on the water, hut they do 

 not lay their eggs in the water. 



Fig. 2:2. Body forms of Collembola. a, Onychiuridae; 

 fa, Isotomidae; c, Smynthuridae. 



the spring is held by the retinaculum or catch on the 

 third abdominal segment (fig. 2'Aa-d). 



The legs of most Collembola are fitted with elabo- 

 rately toothed claws, consisting usually of two parts; 

 the unguis or large claw and, when present, the 

 unguiculus or small claw opposing the unguis. In 

 conjunction with the claw, special guard setae known 

 as tenent hairs may be present. The tenent hairs are 

 often clavate or knobbed (fig. 2'-2>f-g). 



With the possible exception of three genera, respi- 

 ration is cutaneous over the entire body. Womersley 

 (1939) reports that the genera Smynthurus, Smynthu- 

 rides, and Actaletes are provided with true tracheae. 



So far as is known, there are few external sexual 

 differences between individuals. Metamorphosis is 

 lacking; the only external changes between newly 

 emerged young and fully grown adults are progressive 

 intensification of pigmentation and further differen- 

 tiation of segmented appendages. 



The food of aquatic Collembola consists of decaying 

 animal or vegetable matter which usually occurs in 

 abundance in stagnant water, intertidal zones, rain 

 pools, or on melting snow. 



In spite of their relative obscurity, Collembola are 

 believed to be the most widely distributed of all 

 insects in temperate and arctic regions. Many species 

 are cosmopolitan, whereas others, such as those of 

 the Australian fauna, are endemic and typical only 

 of specialized environments. The aquatic or semi- 



COLLECTION AND PREPARATION 

 OF COLLEMBOLA 



Collecting. — Although we are concerned here with 

 aquatic types, it is appropriate to mention also meth- 

 ods used in collecting from moss, leaves, under wood 

 and bark, and from fungi. 



A flat, white enameled pan into which moss and 

 trash can be shaken will permit rapid collecting of 

 some species, especially if a small amount of water 

 is first put in the pan. The insects can dion be picked 

 from the surface with a fine brush. If it is inconvenient 

 to carry a pan in the field, samples of moss, leaves, 

 fungi, or rotten wood may be collected in ice-cream 

 cartons and brought to the laboratory for separation. 

 A few drops of xylol on the surface of the water will 

 prevent most of the jumping forms from escaping. For 

 complete coverage of soil, leaves, or moss, the 

 Berlese funnel can be used most effectively. A vial 

 of 90 per cent alcohol is placed beneath the funnel 

 to catch the specimens as they fall out. 



For aquatic collecting, a sieve frame lined with 

 fine porous nylon netting is recommended. The insects 

 can be picked out with a suction tube and transferred 

 to alcohol vials. To prevent distortion from shrinkage 

 and to preserve color patterns, specimens are best 

 preserved in 90 to 95 per cent alcohol. However, 

 color records should be made as soon as possible 

 since color retention in alcohol is, at best, limited. 



Preparation. — Because of the delicate structure of 

 the Collembola, only the mild solutions suggested 

 below should be used for clearing, staining, or fixing. 

 Carbo-xylol, KOH solutions, and pure xylol are not 

 recommended. 



Direct clearing. — Many species need only bo passed 

 from alcohol through clove oil before mounting. Clear- 

 ing in clove oil requires one to several hours. Xylol 

 added at the rate of 1 cc. xylol to 15 cc. clove oil 

 assists the process in some instances. 



Clearing and staining. — Many Collembola require 

 clearing with caustic and subsequent staining to 

 differentiate key characters used in identification. 

 This applies particularly to those possessing intricate 

 postantennal organs or other sensory apparatus. 

 Treatment in 5 per cent NaOH for periods ranging 

 from a few minutes to several hours will remove 

 pigmentation. Specimens are then transferred to 10 

 per cent acetic acid solution to neutralize the caustic. 

 They can then be stained in an alcohol-base basic 

 fuchsin to the desired intensity. Overstaining can be 

 remedied to some degree by returning to a water 

 wash. After staining, specimens must be dehydrated 

 in 95 per cent ethyl alcohol before final clearing 

 in clove oil. 



