What with the pervasive, invasive and down-right irritating Asian carp so close to the city (O’Brien Lock, anyone?), I took the time to head over to the Shedd Aquarium on Friday to see what the things look like.

The thing about Asian carp is that they’re kind of like… mini-whales. They sit in the current, mouths open, and sift out all the good stuff. The problem? It’s ALL the good stuff. In parts of the Illinois River, researchers say the fish make up about 90 percent of the biomass. And they’re out-competing everything that already lives there.

But most people wouldn’t find them quite so annoying if the fish didn’t have one other, annoying habit: The leaping thing. I can imagine that raining fish would be pretty cool in some circumstances (lost at sea, famine, dream sequence) but after that first time on the river, when you’ve been whacked in the head by a mildly spiny,  but very large fish … well.

James Clark, the Shedd aquarist I talked to says it took two hours to pull a 100 foot net out of the Illinois River during a field study this summer – because of the carp.  He says he’s been out on the river every year doing the same study – and it’s only been really bad the past two years.

Clark says the fish travel in a sort of leapfrog pattern – and that’s why it took them 15 years to get here. He says the parents scatter eggs as a shoal (long, wide group as opposed to a school, a tall group using the whole of the water column) near the bottom of the current.

As they grow up, they move upstream, beyond their parents, eating the same plankton that our native fry (aquarist for “young fish”) would to consume. The native species are shoved out of the way by the carp and… well. It’s a diabolical pattern that puts  the entire river ecosystem at risk.

And the worst part? Turns out the fish aren’t something we want to eat. Clark says in Asia the carp are considered dinner-quality, but that they don’t quite suit American tastes. He says he knows scientists who have eaten them, but that he doesn’t know of anyone who wants to do it again.

Of course, the Shedd doesn’t want us to forget all of our other invasive friends. We’re still paying for past invasions, including the round gobies and the zebra mussels that have invaded the Great Lakes.