Most animals eat more than one kind of food, so food chains join together into a food web. In a pond, a duck may eat weed, snails and small fish. A web shows all these links at once.
A change to one living thing affects others in the web. If a disease kills most of the rabbits, foxes have less to eat and their numbers may fall, while the grass may grow taller. All the energy in a food web comes from the Sun first. Plants trap it, and it passes along the arrows. At each step much of the energy is used for moving and keeping warm, so there are usually fewer animals at the top.
Worked example
In a web, owls eat mice and voles. Voles also eat grass. What happens to owls if the voles die out?
- Owls lose one of their foods.
- They must rely on mice only.
Answer:Owl numbers are likely to fall, and they may eat more mice.
Key words
- food web
- many food chains linked together
- energy
- comes from the Sun and passes along food chains
- top predator
- an animal that nothing else hunts
- population
- the number of one kind of living thing in a place
New questions every time.
NGSS-referenced: 5-LS2-1