HOW EFFICIENT IS A FISH?

摘要

They also recorded the croaks' spectra and found that the fish produced rapid pulses of sound. Each pulse had a peak frequency of 97 Hz and the pulses were also in synch with the buckling movement on the fish's surface. Finally, Boyle and Tricas looked at the position of the anterior hypaxial muscles and found that the muscles were not attached directly to the swim bladder, but to adjacent structures. The duo suspects that when the muscles on both sides contract, they buckle the fish's sides forcing the swim bladder out in front to produce a sound. They also explain that the pyramid butterflyfish's indirect approach is similar to that of unrelated fish and the duo suspects that these butterflyfish have independently evolved the mechanism instead of inheriting it from close relatives.