Really?

From the "So, what were you expecting?" files....

Researchers at the University of Minnesota's Institute of Technology have demonstrated that the shapes of fishes are probably influenced by their hydrodynamic environment. Pretty sure we shouldn't be surprised by that. Tuna and flounder, eels and batfish - they've all been pretty specifically to fit into a particular flow (or non-flow) regime. Of course, the toys that these guys employed are pretty cool. The designed two virtual mackerels and two virtual eels. Then, they made one mackerel move like a mackerel and the other one move like an eel. Same with the computerized eels. Then they raced them through a virtual environment. And guess what? The mackerel that was shaped like a mackerel won, as did the eel that was shaped like an eel.

Actually, that's not a trivial as it sounds. Perhaps it's obvious that a fish in a high flow environment should be more streamlined, but it's not as intuitive that a slow swimmer like an eel is actually better suited with an eel-like body - it's certainly possible that other selective pressures could be driving body shape. This work suggests that, for fish, moving through the water efficiently is a huge factor in being successful.