Trophic levels
A simple A sequence (usually shown as a diagram) of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels. is:
algae → mosquito larvae → dragon fly larvae → perch
All other food chains in an The living organisms in a particular area, together with the non-living components of the environment. can be added together to make a food web. These stages in a food chain or web are called The position of an organism in a food chain, food web or pyramid..
At the bottom of all food chains is a Plants that begin food chains by making energy from carbon dioxide and water.. This is almost always a plant or alga which can A chemical process used by plants to make glucose and oxygen from carbon dioxide and water, using light energy. Oxygen is produced as a by-product of photosynthesis. Algae subsumed within plants and some bacteria are also photosynthetic. to convert carbon dioxide and water into glucose. This provides all the biomass for the food chain. Algae are the producers in the food chain above.
All following trophic levels relate to An organism that obtains its energy by eating other organisms., which cannot make their own food.
The second trophic level in all A sequence (usually shown as a diagram) of feeding relationships between organisms, showing which organisms eat what and the movement of energy through trophic levels. is a herbivore or An animal that eats both plants and meat. called a The name given to an organism that eats a producer. A herbivore.. Mosquito larvae are the primary consumers in the above food chain.
The third stage is a carnivore or An animal that eats both plants and meat. which eats the primary consumer. This is called the An organism that obtains its energy by eating the primary consumer. and is dragonfly larvae in the above food chain.
There may be additional carnivorous consumers which would be called tertiary and quaternary. The final level is a carnivore often called the top or apex predator - in this example, a perch. Organisms at the top of a food chain have no predators.
An organism which eats dead organisms, fallen leaves, animal droppings, etc, and breaks them down into simpler materials. are bacteria and fungi that break down dead plant and animal matter. They secrete A protein which catalyses or speeds up a chemical reaction. on the surface of the dead organisms to break the organism down and then absorb the digested, smaller food molecules.
Common words used with food chains and their meaning
| Word | Meaning |
| Producers | Green plants - they make glucose during photosynthesis. |
| Primary consumers | Usually eat plant material - they are herbivores (or omnivores). For example, rabbits, caterpillars, cows and sheep. |
| Secondary consumers | Eat animal material - they are carnivores (or omnivores). For example, cats, dogs and lions. |
| Predators | Kill for food. They are either secondary or tertiary consumers. |
| Prey | The animals that predators feed on. |
| Scavengers | Feed on dead animals. For example, crows, vultures and hyenas are scavengers. |
| Decomposers | Feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces. |
| Word | Producers |
|---|---|
| Meaning | Green plants - they make glucose during photosynthesis. |
| Word | Primary consumers |
|---|---|
| Meaning | Usually eat plant material - they are herbivores (or omnivores). For example, rabbits, caterpillars, cows and sheep. |
| Word | Secondary consumers |
|---|---|
| Meaning | Eat animal material - they are carnivores (or omnivores). For example, cats, dogs and lions. |
| Word | Predators |
|---|---|
| Meaning | Kill for food. They are either secondary or tertiary consumers. |
| Word | Prey |
|---|---|
| Meaning | The animals that predators feed on. |
| Word | Scavengers |
|---|---|
| Meaning | Feed on dead animals. For example, crows, vultures and hyenas are scavengers. |
| Word | Decomposers |
|---|---|
| Meaning | Feed on dead and decaying organisms, and on the undigested parts of plant and animal matter in faeces. |
