Understand that all organisms in an ecosystem are linked together in a food chain. Destroy the food chain, and you destroy that ecosystem. Destroy enough ecosystems, and we destroy Earth as we know it.
In a pond, you may have the following food chain:
floating algae -> small fish -> large fish -> birds.
- Food chains always start with a plant. The plant is the producer.
- It can convert the sunlight into energy.
- Everything else in the food chain is a “consumer.”
- The arrows indicate the flow of energy.
- (Primary) The small fish eats the algae, and gains energy.
- (Secondary) The large fish eats the small fish, and gains energy.
- (Tertiary) Finally, birds eat the fish.
- When the bird dies, decomposers likes earthworms breakdown the organic matter so it can be absorbed by other organisms.
- Decomposers are not normally placed at the top of the food chain…
- but play an important role to keep the food chain going.
- The top of the food chain consist of “apex consumers.”
- With each transfer, there is a loss of 90% of the energy as heat.
- This means, the next organism up the chain only gets 10% of the energy that was stored.
- I.e. the large fish only got 10% of the energy that the small fish had initially.
- The animal that’s doing the killing - Predator.
- The animal that’s doing the dying - Prey.
Most animals, except humans, live in harmony with the food chain. They eat what they need and all is well. But the human animal, with its superior brain combined with greed often breaks this chain.
- Dumping chemical pollutants into the ecosystem.
- The bad chemicals enter the food chain, and it soon enters the body of the animal.
- Animals will fall sick and die.
- Think of a world without animals.
- Illegal and over-hunting
- If you kill too many primary, or secondary consumers, usually done for profit, then you will upset the food chain. How?
- For the animal up the chain, there is no food left to eat (A lion cannot suddenly change it’s diet to a veg burger, if it can no longer find any deer)
- Eventually it will die, and the problem keeps going up the chain.
- The problem can occur they other way too - kill too many apex predators
- And the primary and secondary animals over-populate the ecosystem
- Leading to over-grazing which can also affect the climate.
- Remember, once the last of the species dies, there is no coming back.
Read https://news.ucsc.edu/2011/07/apex-consumers.html to know what happens when large predators are removed from the food chain.
Finally, a food web is several food chains linked together. Because the real world is more complex.
(Kestin Schulz: Wikipedia)