A CYCLOPS (Water-flea). 



Phylum X, ARTHROPODA; class i, CRUSTACEA; sub-class i, 

 ENTOMOSTRACA; order 3, COPEPODA. 



HABITAT. The various species of Cyclops are abundant in fresh- 

 water streams, ponds, and pools. One is pretty sure to find them also 

 in aquaria and frequently in the ordinary drinking water from our city 

 hydrants. Nearly related forms swarm hi the surface waters of the sea. 

 All feed upon Paramcecia and other Protozoans, Rotifers, and the like. 

 In turn the Cyclops forms the main food of most of the fresh-water 

 fishes while young. They breed so rapidly that it is estimated that the 

 progeny of a single female would number more than four billions in a 

 year if all the eggs hatched and all the young survived to reproduce in 

 turn. The males are smaller and much less abundant than the females. 



APPEARANCE. Individual Cyclops are plainly visible to the naked 

 eye as little white specks swimming about with a peculiar jerky motion. 

 They are about a millimeter in length. By tapping the sides of the 

 aquarium with a pencil one can start them from cover, when their 

 movements may be readily observed. 



Technical Note. If the aquarium is shallow specimens may be captured 

 with a pipette. If the water is too deep for that, use a glass tube open 

 at both ends. Close one end of the tube with the thumb and lower it 

 until the open end is close to the specimen, then release the thumb and 

 the Cyclops will be drawn into the tube with the water. Close the tube 

 again and transfer your Cyclops to a watch glass. Study movements 

 for a short time with a lens, then place the Cyclops in a few drops of 

 water on a slide. Cover, and study with a low power of the micro- 

 scope. If the little animal moves about too rapidly add a drop of 

 ether to the water, or use glycerine instead. A few fibers of cotton 

 placed between the slide and cover glass may sufficiently restrict the 

 movements. 



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