Answer:
A small change in our ecosystem could forever impact the whole web. For example, if bees were to go extinct, then flowers wouldn't be able to reproduce (since bees fertilize the flowers). Meaning the flowers would die out. And a lot of living things, including humans, depend on bees. Or let's say that a sharks were to go extinct. They play a major role in our ecosystem, because they eat fish and other sea creatures. The prey would then grow in population. Which would lead to a disaster. So in short terms, every creature in the ecosystem is vital to maintain the balance. I hope this helps!! :)