Food Chain
Introduce this section with the food chain discussion card called
‘Under the sea’.
Food chains are a flow of energy
Food webs exist in a delicate balance. If one animal’s source of food disappears, perhaps from a natural cause such as a drought or a killer disease, many other animals in the food chain are affected. Some populations may decline, and some explode. Humans are usually at the top of the chain and are often responsible for disrupting food webs.
All living things depend on one another to survive. Put simply, a food chain shows how each living thing gets food. At the bottom of the food chain are plants like grass on land, and phytoplankton or kelp in the sea.
Plants get the energy they need from the sun, and this energy is passed along the food chain as they are eaten by other living creatures.
Disrupting a food web can be a disaster!
A polluted section of the sea (e.g. from an oil spill) might block out sunlight which kills the phytoplankton, which are tiny aquatic plants at the bottom of the food chain. This means there are fewer plants for shrimp and small fish to feed on, so some starve. Larger fish have fewer shrimp or small fish to feed on and so they may starve too, or move to another feeding ground. This increases the pressure on other species trying to share the same food source.
Here is a simple food chain. Energy passes along the chain in the direction of the arrow. plankton shrimp
herring
cat
Some animals and fish are herbivores, and eat only plants, others are omnivores and can eat both plants and animals.
Carnivores eat only animals and scavengers eat whatever they can find – sometimes even dead animals. An animal which lives by killing and eating other animals is called a predator.
An animal is prey when another animal hunts it for food.
Growing human populations are demanding more food, and this puts pressure on many food chains. In some areas, fishers may catch too many fish. In
‘Under the sea’.
Food chains are a flow of energy
Food webs exist in a delicate balance. If one animal’s source of food disappears, perhaps from a natural cause such as a drought or a killer disease, many other animals in the food chain are affected. Some populations may decline, and some explode. Humans are usually at the top of the chain and are often responsible for disrupting food webs.
All living things depend on one another to survive. Put simply, a food chain shows how each living thing gets food. At the bottom of the food chain are plants like grass on land, and phytoplankton or kelp in the sea.
Plants get the energy they need from the sun, and this energy is passed along the food chain as they are eaten by other living creatures.
Disrupting a food web can be a disaster!
A polluted section of the sea (e.g. from an oil spill) might block out sunlight which kills the phytoplankton, which are tiny aquatic plants at the bottom of the food chain. This means there are fewer plants for shrimp and small fish to feed on, so some starve. Larger fish have fewer shrimp or small fish to feed on and so they may starve too, or move to another feeding ground. This increases the pressure on other species trying to share the same food source.
Here is a simple food chain. Energy passes along the chain in the direction of the arrow. plankton shrimp
herring
cat
Some animals and fish are herbivores, and eat only plants, others are omnivores and can eat both plants and animals.
Carnivores eat only animals and scavengers eat whatever they can find – sometimes even dead animals. An animal which lives by killing and eating other animals is called a predator.
An animal is prey when another animal hunts it for food.
Growing human populations are demanding more food, and this puts pressure on many food chains. In some areas, fishers may catch too many fish. In