A quick lesson for those stuck in underwater traffic jams: Don't honk at the fish in front of you. It's probably going as fast as it can. Bluefin tuna (shown) and river trout may be known for their sleek contours, but why these animals evolved their unique shapes, including their pointed snouts and tapered tails, has been a mystery. In other words, are they built for speed or some other consideration? In a study published online today in the Proceedings of the Royal Society B, researchers turned to computer-simulated swimmers for an answer. The team started with generic-looking fish complete with working muscles, and then played evolution. The group watched what happened to those cartoonish shapes when they balanced two goals: Swimming fast and saving energy while doing so. And, sure enough, those hydrodynamic considerations created fish that actually resembled real fish. So don't expect fish to speed up any time soon. These animals have evolved to be the best swimmers they can be.
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