Life And Death In The Food Web

I spent this morning being a mackerel. An unusual, but enjoyable start to the day. A dozen strings connected me to students (the predators!) in what soon become a tangle of marine science excitement, a simplified food web. Each student proudly wore a species badge, some were turtles, some sharks, a few fish, plankton, inverts and the odd mammal for good measure. Everyone was connected.

“So what would happen if we fished all the mackerel out of the ocean?” I ask, dropping all my strings.

“I’d die!“ exclaims the young one who didn’t have any other prey to choose from, and another whose only string now hung limply over the floor.

“I’ve still got food.” A voice from the back, non-pulsed.

“No, they’re mine”, came a retort. When one population collapses, those that feed on it, turn to another. And competition for resources rises.

I pick up my strings and look for the kids that couldn’t wait to be sharks. “So what if we killed you off? And there were no top predators.”

“Nothing?” came a voice, confused, why bother asking that?

An uncertain murmur rippled over the students and I looked to the seal “you’re saying if there were no polar bears and no sharks, you wouldn’t be happy about it?”

“No, it’d be great!” she rejoiced.

“There would be a lot of seals, and they would eat a lot of fish, and this would impact other parts of the food web too,” I tell her.

“So, when something changes, everything else can too?”

"Yes."

They’d nailed it. Life is a delicate balance and when we take something out of the food web, everything changes.