1. How can new organisms change food webs?

2. Unit Standards
5.L.4B.1
Analyze and Interpret data to explain how organisms obtain their energy and classify organisms as producers, consumers (including herbivore, carnivore, and omnivore), or decomposers (such as Fungi, Bacteria insects and molds).
5.L.4B.2
Develop and use models of food chains and food webs to describe the flow of energy in an ecosystem.
5.L.4B.3
Construct explanations for how organisms interact with each other in an ecosystem (including predators and prey, and parasites and hosts).
5.L.4B.4
Construct scientific arguments to explain how limiting factors (including food, water, space, and shelter) or newly introduced organisms can affect an ecosystem.

3. How do new organisms change food webs?
Every living thing in an environment is part of a food web. What happens when a new organism move into an environment?

4. How do new organisms change food webs?
In 1935, Australia’s sugarcane fields were being destroyed by two insects. One insect was the greyback cane beetle. The other was French’s cane beetle.

5. How do new organisms change food webs?
Local scientists decided to bring the cane toad as predators to eat these beetles.
Scientists thought the cane toads would eat both types of beetles.
They also thought lizards and birds would eat the toads.
They hoped this would keep the toad population from growing too fast.

6. How do new organisms change food webs?
The cane toads did not do what scientists hoped they would. The toads did not eat the beetles at all.
Instead they ate just about everything else in sight. They ate frogs, rodents, birds, lizards—even pets.

7. How do new organisms change food webs?
Birds and lizards did not eat the toads as expected.
The toads were poisonous to these animals.
Instead the toads ate the birds and lizards.
Without any predators, the cane toad population grew and grew.
The whole food web changed with just one new organism.

8. How do new organisms change food webs?
The cane toads have been in Australia’s environment for over 70 years. They are still causing problems for local farmers.