What would happen if one species went extinct?
Consider a simple food chain.
Krill > Squid > Emperor Penguin > Killer Whale
If one of thse things were to die out, the whole chain would be affected. If the killer whales died out, there would be an abundance of penguins. They would eat too many of the squid. So there is not enough squid to eat, so many penguins would die. There would also be lots more krill. Any remaining squid would have plenty of food to eat, so if they were lucky, the squid population might balance out. As might the penguin population. Then too many krill would be eaten, so not enough squid for penguins. etcetera.
Now what about a far more complex food web?
As you can see, there’s a lot more going on. Krill are the basis for everything. If krill die out, everything dies out unless it can find an alternate food source. What if the squid went? Then what would happen?
Well, as you can see, the only other things that most of these creatures eat is fish and krill. For the krill, it’s one less thing eating them. But for the fish, everything is going to be picking on them now.
What if instead, it was the leopard seals who went Kaput? There would be less Penguins, Crabeater sels and Petrels, more fish and squid, and less Krill. This would mean everything suffers. Everything.
The same wave applies to all of the above creatures:
This is exactly what would happen. As you can see, just after the prey has gone down, so does the predators. You can also see that at the high points, there is always more prey than predator. This is becuase the predator needs to eat more prey, because more often than not, the predator is larger than the prey.
But as I hope you’ve learned, affecting just one thing will affect the whole food web. And that includes us.