3/8 



THE GUIDE TO NATURE 



posterior part of the body is drawn out 

 into a long spine. In Bosmina the bod)' 

 is peculiarly humped, the antennae arc 

 reduced in size and the head is prolonged 

 into a long rostrum which resembles an 

 elephant's trunk. This rostrum varies 

 in the different species and forms, being 



mm&mz 



Together with the nymphs of dragon- 

 flies and certain of the Hemiptera or 

 bugs they form the great body of preda- 

 tory animals that are ever on the watch 

 for unwary creatures of herbivorous 

 habits. These water-mites are attractive 

 little animals, both as objects for the 



COMMON HAPIIXIA WATER FLEA. 



THE CHYDORUS WATER FLEA. 



almost straight to considerably curved. 

 In Chydorus sphccricue the body is al- 

 most round and there is a long rostrum. 

 These are but a few examples of the 

 large number of species and varieties of 

 these little water fleas. Only a compar- 

 atively few species live on the bottom 

 among algae and other plant life. The 

 great majority swim about in the open 

 water forming a considerable part of the 

 plankton. These animals are economi- 

 cal! v of "reat value furnishing: food for chaete worms and the larvae of certain 



microscope and as inhabitants of the 

 aquarium. Many species occur in fresh 

 water, usually associated with bottom 

 vegetation in shallow water. One group 

 in particular (Unionicola) is parasitic in 

 fresh water mussels, and many species 

 of other groups in the larval and pupal 

 state attach themselves to aquatic ani- 

 mals. 



In point of numbers the most abundant 

 animals in our algal world are the oligo- 





O.I MM. i 



O.I MM 



BOSMINA WATER FLEA WITH MAGNIFICATION OF REAR AND TWO STYLES OF HEADS. 



nearly all small and young fish and for 

 several adult fish of high economic value. 

 Among the most conspicuous animals 

 in our algal mass are the little water- 

 mites or Hydrachnids. These conspic- 

 uously colored creatures — red, brown, 

 blue — actively wander over the plant life 

 hunting for their prey which may be 

 larval insects, crustaceans, or worms. 



flies, of the genus Chironomus. These 

 animals are rendered quite inconspicuous 

 by their color which is of the same deli- 

 cate pea-green as the filamentous algae, 

 and is caused by the immense amount of 

 alga? they have eaten. So rapidly do 

 some of these oligochaete worms multiply 

 by budding (every two or three days) 

 that in a short time thev are so numerous 



