14 College of Forexfri/ 



The striking- feature of the plant life in many habitats is 

 the presence of large quantities of the water plants known 

 as filamentous alga-, which cover the bottom as well as the 

 higher plants like a thick blanket, and greatly modify the 

 natural character of the bottom. It seems probable that the 

 great wealth of animal life in pails of this lake is largely 

 due to the presence of this lowly plant, which provides a rich 

 food supply for the invertebrate animals. 



Below a depth of twelve feet the bottom of the lake, as far 

 as examined, is covered with soft, black mud on which little 

 or no vegetation grows excepting a few species of alga>. and 

 animal life is consequently reduced in both number and 

 kind. 



LSTVEBTEBKATE AxiMAL LlVK IX OxKIDA LAKI-; 



The floor of this beautiful lake, in the bays and the 

 shallow areas bordering the shore, is carpeted with a great 

 variety of plants, many of which, like the feathery Water 

 Milfoil (Myrioplii/lhun), form miniature aquatic forests in 

 the bays and other sheltered places. The rocks, the plants 

 and the whole bottom in many places is covered with masses 

 of the delicate green water plants, the filamentous alga\ 



Among this wealth of plant growth many kinds of animals 

 live in great abundance. The alga 1 are inhabited by the 

 young or larvte of flies, and small-jointed worms related to 

 the earthworms (Oligocha?tes), whose bodies are as green as 

 the color of the alga 1 which they have eaten. Myriads of 

 little crustaceans, called Scuds or Water Fleas (Amphipods 

 and (Tadocera) dart about and thousands of fresh-water 

 Sowbugs (Isopods) crawl over the filmy masses of alga?. 

 The little spider-like mites (Ilydrachnids) actively search 

 the alga 1 and weeds to prey upon the smaller animals. The 

 young or nymphs of Dragon-flies (Odonata) lie in ambush 

 among the alga* or bury themselves in the muddy bottom : 

 the young of May-flies, with their feathery gills attached to 

 the outside of their bodies, and the Caddis-fly larvae, with 

 their curious houses or cases made of grains of sand, snail 



