🕸 TREE 206: Stupid fish

California killifish live along the coasts of southern California. Some of them are real idiots. They swim and wiggle in conspicuous ways that make them 30 times more likely to be eaten by birds.

If we were into anthropomorphising, we might say they need to get smart and start taking responsibility for their dangerous behaviour. But then we would be the idiots. It’s not the killifishes’ fault. Each one of them is being controlled by a parasitic flatworm wrapped around the outside of its brain.

The flatworm needs the fish to be eaten by a bird because the worm lays its eggs in the bird’s gut. When the bird poos out the eggs, they are eaten by a snail and hatch inside the snail causing the snail to become infertile. Once they’ve finished with the snail, the worm larvae swim out into the water like little tadpoles looking for killifish to inhabit. They slip in through the gills and another little fish starts its death dance.

So that’s pretty horrific.

It’s also important. The flatworms keep the snail population under control and enable a bunch of fish-eating birds to flourish.

When you see something strange, it’s almost certainly a small visible part of a complex system which cannot be understood without doing some hard work.

This week we’re thinking about systems and why we need to think about systems.

Grow slowly
Jeff

Sources: 1, 2, 3, 4, 5 (If you only look at one of these sources, look at 5.)

Photo: Ben Cantrell

Somehow I’ve done 10 months of TREE without a single Primus song. I can only apologise.

The Memory of TREE playlist – every song from every email: