Living Things in Ecosystems

Homes for Living Things

habitat: an environment that meets the needs of an organism

• some habitats include whole ecosystems– birds that can fly from place to place

• others are only a small part of the ecosystem– fungi that can only be found in certain places

on the forest floor

• some habitats overlap and include the same areas– organisms compete – try to get the same

food/space• 2 species of fish living in the same pond trying to

get the same insect

– very different organisms do not need to compete

• birds and caterpillars live in the same habitat but have different ways to meet their needs

– birds eat caterpillars while caterpillars eat leaves

Roles

• niche – an organism’s role– niche includes all the ways it meets its basic

needs• how it gets shelter, how it produces young, and

how it gets food and water

• sun main source of energy for all living things– animals eat plants, which use sunlight to grow

or animals eat other animals that eat plants, which use the sunlight to grow

• food chain: the way energy moves through ecosystems– connect and overlap to form food webs

• food web: shows where many types of living things in a community get food

– food chains have 3 levels• green plants and some protists/monerans are

producers – they make their own food• consumers eat other living things for energy – insects,

frogs, lions, humans• decomposers feed on the wastes of plants and

animals or on their remains after they die– they return nutrients to the soil for plants to use as the cycle

begins again

Causes of Change• as organisms meet their needs they affect

their environment– usually changes are small and help keep

ecosystem stable– some changes affect other organisms

• insects are in a bird’s habitat• birds eat insects and that keeps the insect

population from growing too large– when there are too many birds eating insects the

population reduces quickly : there will not be enough insects for birds to eat

• to balance out the habitat (keep stability) some birds will leave the area, some birds will die, and fewer baby birds will be born

– this allows the insect population to grow

– some changes affect nonliving parts of the ecosystem

• worms/lichens make soil of their habitats better• prairie dogs dig holes in rangeland

– this is a negative change for humans because the holes are dangerous for grazing cattle and sheep

– over time most changes in nature balance out and stability is kept

Summary

• environment that meets the needs of an organism is its habitat

• organisms role within its habitat is its niche

• as organisms fulfill their role, they affect both living and nonliving parts of the ecosystem