More on the goosefish (fond memories of goosefish during my years at the Sea Lab) and the evolution of its pectoral fins. The pectoral fins of a fish are the paired structures behind the gills, analogous to a bird’s wings. Most fish use these for steering and turning. Goosefish are pediculate fishes, in that the pectorals are shaped like little arms, and even seem to bend at the elbows. And, yes, the fish can actually walk across the bottom with these. Fish have carpal bones in their fins (i.e.: fingers), but in most species these bones are too small to be seen externally. The carpal bones of the goosefish are greatly elongated, with fin webbing in between the fingers. This is what gives the fin that unusual bend to it. While the pectorals of most fish are behind the gills, anglers are the only group of fish whose gills actually sit behind the pectorals. The paired pelvic fins, normally found on a fish’s chest, are also unusual in this species in that they are found just under the chin and form a pair of little kickstands for the head to rest on. This puts the mouth in a more upright position and helps make hunting more efficient. See how much more vertical a hunting angler looks when propped up on these fins (photo 1). From personal experience, when approaching a goosefish in this vertical position, dont put your hands anywhere close to it :D Camouflage also helps tremendously when hunting :D (photo 2, 3). Unlike their famous cousins, mudskippers, catfish, the Pacific leaping blenny, all of whom walk on land, the goosefish, like all anglers, is a deep water fish. So, what is the driving force behind the adaption of walking at such depths? Perfecting the vertical upright position that greatly enhances the threatening position (similar to a bird that ruffles its feather in an attempt to look bigger than its predator, or a puffer that blows up, making it also appear bigger)?
Posted on: Sun, 28 Dec 2014 15:35:23 +0000
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