CHAPTER X 
ANIMAL COMMUNITIES OF THE TENSION LINES BETWEEN LAND 
AND WATER 
I. INTRODUCTION 
Margins of bodies of water, swamps and marshes, and temporary 
ponds are on the border-line between land and water. Swamps and 
marshes are areas occupied by plants whose stems, leaves, and blossoms 
are in the air and whose roots are in the water or very moist soil, 
throughout the year. Areas covered by grasslike plants are commonly 
called marshes, while those covered by trees are called swamps. 
Swamps and marshes usually contain water the year round and are 
commonly either directly connected with some permanent body of water 
or are fed by springs. Others are dry in summer, and possess an active 
aquatic fauna only in spring and after heavy rains. Our area, being in 
a region of glaciation, represents a portion of one of the great marsh areas 
of the world. Geologically speaking, however, these features represent 
the positions of lakes and serve to show us the fate of our small lakes 
and ponds. Classification of these communities is difficult, but they 
may be divided into temporary and permanent swamps and marshes 
and into margins of lakes, ponds, and rivers. 
II. COMMUNITIES 
I. PERMANENT WATER, SWAMP, AND MARSH COMMUNITIES 
a) Lake-margin marsh sub-formation (senescent pond, or emerging 
vegetation pond association) (Stations 30, 30a, 31).—About the margins 
of lakes and ponds there is often a girdle of bulrushes and cattails (Fig. 
116) which has a characteristic animal community. The sub-aquatic 
stratum is made up of pond animals and has been considered already in 
chap. viii. There are a few characteristic animals which live chiefly 
above the water. The diving spider (Dolomedes sexpunctatus) (Fig. 95) 
crawls about on the marsh vegetation and dives beneath the water for 
prey. The long slender spider (Tetragnatha laboriosa) is common among 
the bulrushes (138). At the base of the rushes and sometimes crawling 
near the top is the snail (Succinea retusa) (gt). Common frogs (Rana 
pipiens and clamata Dan.) (Fig. 116) and the cricket-frog (Acris gryllus) 
hop about in the water (139). 
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