175
175- Ecology and food webs
WE CAN LOOK AT NATURE in the same way that we look at a
complicated machine, to see how all the parts fit together. Every living
thing has its place in nature, and ecology is the study of how things live in
relation to their surroundings. It is a relatively new science and is of great
importance today. It helps us understand how plants and animals depend
on each other and their surroundings in order to survive. Ecology also helps
us work toward saving animals and plants from extinction and solving the
problems caused by pollution. Plants and animals can be divided into
different groups, depending on their ecological function. Plants capture
the sun’s light energy and use it to produce new growth, so they are called
producers; animals consume (eat) plants and other animals, so they are
called consumers. All the plants
and animals that live in one
area and feed off each other
make up a community.
The relationships between
the plants and animals in a
community is called a food
web; energy passes through the
community via these food webs.A frog forms a link between two
different food webs—the pond and
the meadow food webs.CARNIVORE
The adult frog is carnivorous; it
catches flies and other small
creatures.OMNIVORE
Many small fish are omnivores, feeding
on whatever they can find—from water
weeds to tiny animals
such as tadpoles.Plants form the
beginning of the
food chain in a pond,
as they do on land.HERBIVORE
As a young tadpole, the frog is a
herbivore, eating water weeds.DETRITIVORE
Certain types of worms and snails are
called detritivores because they eat
detritus, or rotting matter, at the
bottom of a pond or river. They help
recycle the materials and energy in
dead and dying plants and animals.During the spring, the
frog is part of the pond
food web. In the fall,
it moves on to land and
becomes involved in
the meadow food web. The fox is a
top carnivore in
the meadow
food chain.FOOD CHAINS AND FOOD WEBS
A plant uses the sun’s energy to grow. A herbivore (plant eater) eats the
plant. A carnivore (meat eater) or an omnivore (plant and meat eater)
then eats the herbivore. This series of events is called a food chain.
ECOSYSTEM
A community and its
surroundings, including
the soil, air, climate, and the
other communities around
it, make up an ecosystem.
Earth can be seen as one
giant ecosystem spinning
through space. It recycles
its raw materials, such as
leaves and other plant
matter, and is powered
by energy from the sun.
KINGFISHER
Some carnivores are called
top carnivores because they
have almost no predators.
Their usual fate is to die of
sickness, injury, or old age,
at which time they become
food for scavengers. The
European kingfisher shown
above eats a wide variety of
food, including small fish
such as minnows and
sticklebacks, water snails
and beetles, dragonfly
larvae, tadpoles, and small
frogs. The kingfisher is
therefore at the top of a
complex food web.Meadow
food webPond
food
webThe European kingfisher has little to
fear. Its brightly colored plumage
warns predators that it tastes bad.
The kingfisher is well named—it
is extremely skilful
at fishing.