Life abounds in the shallow lakes and ponds. Calm, protected John’s Lake
offers a fine example of how a complex aquatic plant-and-animal
community can exist in balance in a confined space. The water teems with
the microscopic algae, protozoans, and rotifers that sustain the barely
visible zooplankton. Dancing, flitting, hopping, and swaying through the
water, these zooplankton in turn support the larger plankton-eating
animals.
Dragonflies and damselflies shoot past, crackling their wings, and perch
in the bog grass. Looking into the shallow water, you will see a wealth
of small animal life. A spotted frog swims into view, floating to the
surface beside a lily pad so that its eyes protrude above the water.
The ribbonlike form of a leech swims across the bottom toward deeper
water. Looking closer, you see that the water swarms with bizarre
shapes—water boatmen propelling themselves with oarlike appendages, a
gliding mayfly nymph, then a predacious diving beetle surfacing,
grasping a bubble of air beneath its shiny brown wing plates and
disappearing downward again—the bubble’s edge shining silver—into the
brown bottom debris. Suddenly a whirligig beetle sets the surface to
spinning, wrinkling the view below.
Everywhere in the water there is animal life, forms that are attached,
free-swimming, crawling on the bottom, and clinging to or swimming on
the surface film. The gray, slimy encrustation on a sunken log looks
like a covering of lichen but is really a freshwater sponge, a colonial
animal that feeds by filtering minute plankton from the water. Another
attached creature is the barely visible hydra; this twig-shaped
predator, related to marine jellyfish, captures water fleas and other
small animals in its several poisonous tentacles.
Water beetles, backswimmers, water boatmen, and many other creatures
move about more or less freely in the water, propelling themselves along
with jerky movements. Suspended between surface and bottom are the
zooplankton, the tiny water fleas, cyclops, daphnia, and others, which
feed by filtering minute algae. On the bottom and below live scavenging
worms. Water striders skate on the surface film.
Along the shore, frogs, salamanders, garter snakes, and water shrews are
hunting. Dabbling and diving ducks patrol about, tipping or submerging
for the bottom plants. Moose tracks circle the muddy shore. Because it
produces vegetation abundantly, John’s Lake sustains a great diversity
of animal life.