How fish move
There are fish tales and then there are fish tails. And a report from Harvard researchers in the current issue of the journal Biology Letters seems to demonstrate that previous theories about how bony fish move through the water were, well, just fish tales. Scientists have long believed that sunfish, perch, trout, and other such bony fish propel themselves forward with the movement of their tails, while their dorsal and anal fins — the fins on their tops and bottoms — work primarily as stabilizers. But using a new form of laser imaging device, Brooke Flammang and colleagues at Harvard’s Museum of Comparative Zoology (MCV) have discovered that “the dorsal and the anal fin make a great contribution to the caudal [tail fin] wake,” and thus are additional propellers, and not just stabilizers. Flammang’s group made this discovery with help from “a brand-new laser imaging device that allowed us to get an instantaneous...