1. Ch. 5: Predators, Prey & Competition
Vocabulary:
ecosystem, predator, prey, resource, compete, survive

2. Ecosystems
All of the things on Earth, both living and non-living, are part of an ecosystem.
Everything from the plants and animals that live in an area to the water, sunlight, soil, rocks, and air make up an areas ecosystem.
There are many different types of ecosystems on the planet.

3. Ecosystems: Tropical Rainforest
Tropical Rainforests get a lot of rain every year.
That’s why they are
called rainforests.
They are also usually
located in the area of the
Earth known as the tropics.
Tropical rainforests have the most biodiversity of any place on the planet.
Because there is so much rain, fruit trees produce all year long, which leads to more insects, which leads to more birds, which leads to more predators, on and on and on.

4. Ecosystems: Subtropical savannas
Subtropical savannahs are flat grasslands usually found near deserts outside the tropics.
Many different types of animals live on grasslands and have adapted to living in tall grass.
These adaptations usually involve raising the head to see above the grass, or colorations that allow them to blend in with tall grasses.

5. Ecosystems: Deserts
Deserts are dry arid places, that sometimes have sand and sometimes do not.
Because of the lack of water all the organisms that live in the desert have adapted to gather water from other sources than what we normally do.
For example: the pack rat gets its water from eating plants; and the dung beetle allows dew to collect on it every morning and drinks it when the water bubbles get big enough to gather.

6. Ecosystems: Oceans Oceans make up 75% of the earth’s surface.
Most of the water on Earth is located in the oceans of the world.
The plants and animals that live in the ocean have adapted the ability to either float or swim.
Some have even developed the ability to breathe underwater by way of gills, which are different than the lungs you have.

7. Ecosystems: Temperate Grasslands
Temperate Grasslands are large plains of grass found in North America, Asia, and Australia.
Because of the winds that sweep across these grasslands, not many trees grow here.
Most of the animals who live on temperate grasslands have adapted the ability to run quickly away from predators and large shaggy coats for the colder winters.

8. Ecosystems: Temperate Forests
Temperate forests are located outside of the tropics, but below the polar regions of the planet.
Temperate forests have moderate summers and cold winters.
Most of the plants that live in temperate forests have adapted leaves that shed in the winter.
Most of the animals that live in temperate forests have adapted to this lack of food by entering hibernation in the winter.

9. Ecosystems: Coniferous Forests
Coniferous Forests form the boundaries between Temperate Forests and the Polar Regions of the world.
Coniferous plants are specifically adapted to deal with cold weather better than than their temperate cousins.
Coniferous plants have small needle-like leaves that do not shed, so that they can absorb as much sunlight as possible when it is available.

10. Ecosystems: Polar Regions
Polar areas, or tundra, are found near the north and south poles.
The summers are very short and winters can be dark all day long for up to 6 months.
Often in these areas there is a lot of snow.
The plants have adapted to be short and can grow very fast on the little sunlight they can get during the spring and summer.
Animals are often white to blend in with the snow and small because of the lack of plant life, but have an insulating layer of fat called blubber in order to stay warm.

11. Predators and Prey
We know that plants can make their own food using chlorophyll.
Animals, on the other hand, cannot.
Because of this, animals fall into one of two categories: predator or prey.
Animals that eat other animals are called predators.
Animals that are hunted by other animals are called prey.
Sometimes, one animal can be both a predator of some animals and prey to others.
Snakes are both predator and prey. They eat small animals like rats and mice, but they are also eaten by other animals, like hawks.

12. Predators and Prey
In a healthy ecosystem, predators and prey are pretty balanced.
Usually there are lots of prey animals, and a few predators to feed on them.
But many things can alter an ecosystem and throw it out of balance.
Animals in an ecosystem that is thrown out of balance are not dumb.
Usually, they will not remain in an area that lacks what they need and they will move away.

13. Predators and Prey: Sickness
If a disease infects an ecosystem, it can be thrown out of balance.
Let’s go back to the hawk and mouse example from earlier:
A disease affects the mice in the forest, killing a lot of them.
What happens to the hawk population?
Or, a disease affects the hawks in the forest.
What happens to the mouse population?

14. Competition
Sunlight, food, water, and living space are needed for all living things to survive.
But oftentimes, species of plants and animals all want the best of each of these.
In order to get the best food, water, sunlight patch, or living space animals and plants must compete with each other.

15. Examples of Competition
Animals compete most often for food:
Snakes, hawks and owls all eat mice.
If a disease kills most of the mice in the forest and the owls are the ones that are able to catch more mice than the hawks or the snakes, what happens to the hawk and snake populations?
Plants compete, too:
Trees have large roots that stretch for long distances.
They need a lot of water and nutrients from the soil.
They adapted to have large branches and many leaves to shade the area around their roots, so that other plants won’t get enough sunlight at the bottoms of the trees and take the nutirents in the soil from them.

16. Questions about Chapter 4
1. Foxes eat rabbits. What happens to the foxes if something happens to the grass that the rabbits eat?
2. Frogs eat insects. If the number of frogs goes down, what happens to the number of insects?
3. In the Great Plains ecosystem, wolves and mountain lions eat buffalo, antelope, and deer. The deer, buffalo, and antelope eat plants. Which animals are the predators?
4. Give and example of two living things competing for a resource.
5. Name 5 nonliving resources in an ecosystem.