Ecology examines the relationship between living things and
their environment. Animals adapt to the particular conditions of an environment
and take on a specific role, such as predator or prey. This role is known as
their ecological niche. There may be herbivores that eat plants, carnivores
that eat herbivores, and omnivores that eat both. This progression from plants
to carnivores is called a FOOD CHAIN.
Communities of animals and the environments with which they interact
are called ecosystems. They include entire food chains. The grassland of the
African savanna is a large ecosystem. There are plants, grazers such as zebra
and wildebeest that eat the plants, and carnivores such as lion and leopard
that prey on the grazers.
The harpy eagle’s niche is that of a predator in the forests
of South America. It has special adaptations, such as short, broad wings so it
can fly between trees. There are many niches in a particular environment, but
all animals have to compete with other members of the community for resources,
such as food. An animal may not be able to dominate a niche forever.
A habitat is an area, such as a seashore or a woodland, that is home
to certain types of animals. Some habitats support a wide variety of living
things. Others have fewer niches and therefore support fewer species, though
they may gather in large numbers. King penguins are one of the few animals that
can survive in the harsh, cold conditions of the Antarctic.
Animals obtain energy and nutrients by eating other
living things. The flow of energy from one living thing to another is called a
food chain.
Plants get their energy directly from the sun and so are at the
bottom of almost all food chains. Called producers, they provide energy to the
herbivores that eat them. Herbivores are called primary consumers. They are
eaten by carnivores (secondary consumers). The animals that eat the secondary
consumers are called tertiary consumers. Many carnivores eat herbivores and
smaller carnivores, so can be secondary consumers and tertiary consumers. There
are fewer animals at the top of the food chain than at the bottom.
Within animal communities, there are many food chains. Many
animals, such as foxes, eat a variety of foods, so chains can be
interconnected, creating a food web. Even when animals die, they become part of
a food chain. They decay, releasing nutrients which become food for a living
thing.
