... The two problems which face every organism are those of maintaining its own life and continuing its race. Its youth is devoted entirely to satisf… - Ann Haven Morgan

s are transparent microscopic animals which live in fresh or salt water. They abound in the surface waters of great lakes, and swarm through the shallows of ponds and bogs; there is scarcely any stand of soft water, whether transient puddle or rain-barrel or fountain-basin, where rotifers can not be found. They live in ponds and lakes, providing a large part of the food for small s and worms and are thus indirectly a large source of food for fishes.

Among the s and the water weeds of the shallows, lurk es, s, mud minnows, and young . All of these forage upon snails, crustaceans, and insect larvæ, especially the tempting mayfly nymphs which they find there. s float with their heads just out of water; of all frogs these belong most thoroughly in the pond. Equally at home in it are the painted turtles, and the spotted turtles often found with them … In May and June stumps and floating logs usually carry a load of one kind or the other. They forage in the shallows taking a heavy toll of tadpoles, snails, dragonflies—a miscellaneous bill-of-fare which they always eat under water. Snapping turtles frequent these waters also, catching anything within reach of the lightning-quick thrusts of their heads—fishes, tadpoles, frogs, or crayfishes, as well as the smaller game of insects and worms.

Different waters hold their own special communities; the dainty glen stream shelters companies of mayflies in its swift riffles; pond shallows and meadow brooks are the homes of lurking ; and wayside puddles are populous with mosquito wrigglers and . In all these places living things must contend with winter cold and summer drought, with storms and flood waters. In winter the pond populations drop to the bottom, frogs and turtles dig under mud and broken plants, whirligig beetles hide under banks to come out with every warm spell, and fresh water sponges are packed in tough covered capsules. In summer when its own pool dries up the water boatman flies to some other pond but many caddis worms burrow into the mud bottom and endure the drought as best they can.