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307- Lake and river wildlife
THE WATER IN LAKES and rivers is teeming with all kinds of
life. Grasses, reeds, and other plants grow along the water’s
edge, providing food and shelter for insects, nesting birds,
and mammals, such as water voles and muskrats. In rivers,
the fast-flowing water sweeps away plants, but in lakes, tiny
floating plants are food for small creatures, such as water
fleas and shrimps, which are, in turn, eaten by bigger fish.
Larger, floating waterweeds provide shade for basking fish.
Fallen leaves, animal droppings, and rotting plant matter form
a rich mud at the bottom of rivers and lakes, where worms,
snails, and other small organisms live. Today, many lakes and
rivers are suffering from serious pollution. Industrial
chemicals, farm fertilizers, untreated sewage, and a host of
other damaging substances discharged into lakes and rivers
have upset or destroyed the natural wildlife balance.GIANT oTTER
The largest member of the otter family
lives in South America. The giant otter
grows to more than 5 ft (1.5 m) long
including its tail. It hunts catfish,
piranha, and other fish. Unlike
other otters, the giant otter
prefers to stay in streams
and pools and is not
often seen on land.
Today, this otter
is very rare
and is on the
official list of
endangered
species.MUSKRAT
The muskrat is a rodent that usually eats
water plants, but also feeds on small
animals such as fish, frogs, and
freshwater shellfish.CRAyFISH
The crayfish, found in rivers, is a freshwater
relative of saltwater lobsters. It is active mainly at
night and walks along the riverbed on its four
pairs of legs, eating a wide range of food, from
plant matter to worms, shellfish, and small fish.FALSE MAp
TURTLE
one of the
many water
creatures that
suffer from
pollution of rivers and
lakes is the false map turtle
from North America, shown
here. The harmful chemical
waste that we pour into the
water has also reduced this turtle’s food
of snails and shellfish.RIvER pLANTS
The speed of the water in a river has a great effect on the
wildlife. In a fast river, the water sweeps the river bed clean of
sand and mud, leaving only pebbles. Nothing can grow
in the middle of a river, and the riverbank
consists mainly of plants, such as willows,
that hang over the water. In a slow
river, sand and mud can settle,
and plants such as irises take
root more easily.Pond weed is food
for many different
lake and river fish.RUddy dUCK
The ruddy duck is found in
open waters in many parts of
Europe. It has a stiff, upward-
pointing tail and dives in search
of plants, small water insects,
larvae, and worms.FRESHWATER
The water in lakes and rivers is
called freshwater. Although it
makes up only about 0.03 percent
(that is, 1 part in 3000), of all the
water on Earth, freshwater is
home to thousands of different
plants and animals.pIKE
The northern
pike is a large,
fearsome predator
with a huge mouth and
sharp teeth for seizing many
kinds of fish, as well as frogs, water birds,
and small mammals. pike live in lakes and slow-moving
rivers; the biggest pike grow to more than 3 ft (1 m) long.Muskrat swims
powerfully with its webbed
back feet and uses its long,
hairless tail as a rudder
for steering.Pickerell
weed
grows at
the water’s
edge of
lakes and
rivers.US_307_Lake_river_wildlife_1.indd 307 22/01/16 11:10 am