CHAPTER XII 

 LEECHES 

 Hirudinea 



Leeches possess much more beauty and interest than their 

 reputation credits them with. IMost of them are marked with 

 concealing colors and patterns, browns, greens, and blacks, 

 picturing upon them the broken shadows and water-soaked 

 leaves of their natural background and hiding them in it. They 

 are sensitive to the slightest vibration of the water, to shadows 

 passing over them, and to small changes in the flavor of the 

 water around them. Their whole set up is one of exquisite 

 efficiency for their mode of living. 



Form and habits of leeches. — The external features most 

 essential to a leech are the strong muscular suckers at each 

 end of its body and the sucking mouth which may or may not 

 be armed with jaws (Fig. 115). Leeches are segmented worms 

 like bristleworms and common earthworms and belong to the 

 Phylum Annelida. Each segment of the body is creased by 

 two to sixteen superficial wrinkles. These are not easy to dis- 

 tinguish from the true furrows which separate the segments, 

 especially since the number of these superficial rings varies in 

 different parts of the body, there being more in the middle 

 segments and fewer in those near each end of the animal (Fig. 



115)- 



Leeches are hermaphroditic, and like the earthworms, pairs 

 of animals mate even though each one has complete male and 

 female organs within its own body; thus the eggs of one ani- 



148 



