FLICKR, PRILFISH
A diverse group of long-finned marine vertebrates and invertebrates that last shared a common ancestor 550 million years ago use the same fin motion to swim with maximal speed in a rare example of a mechanical explanation for convergent evolution, according to a study published today (April 28) in PLOS Biology.
Flatworms, cuttlefish, rays, and triggerfish are among the 1,000 species that belong to a group known as the median/paired fin swimmers. These animals move by rippling a fin that runs the length of their body. When researchers from Northwestern University measured the height of the ripples and the distance between them in videos of 22 unrelated species from three different phyla, they found that the undulations were consistently 20 times as long as they ...
