Copyright © 2007 Dorling Kindersley
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.