What is Three-spined stickleback?
[[File:Gasterosteus aculeatus.jpg|thumb]] The '''three-spined stickleback''' (''Gasterosteus aculeatus'') is a species of [[stickleback]] in the genus ''[[Gasterosteus]]''. It is found in most inland and coastal waters north of 30°N. It has been a subject of scientific study for many reasons. In its different forms or stages of life, the three-spined stickleback can be a bottom-feeder or a planktonic feeder in lakes or in the ocean. It is also able to eat terrestrial prey fallen to the surface. == Description == The body is laterally compressed. The tail's base is slender. It has three spines that give the fish its name (though some individuals may have only two or four). Dorsal coloration tends towards a drab olive or a silvery green, sometimes with brown mottling. The pectoral fins are large, with 10 rays. The [[dorsal fin]] has 10–14 rays. All spines can be locked in an erect position. The body doesn't have scales, but is protected by bony plates on the back, flanks, and belly. They have silvery bellies and flanks. == Distribution == === Northern Hemisphere === The three-spined stickleback is found in the [[Northern Hemisphere]], where it usually inhabits coastal waters or freshwater bodies. === North America === It can also be found in [[North America]], in which it ranges along the [[East Coast of the United States|East Coast]] from [[Chesapeake Bay]] to the southern half of [[Baffin Island]] and the western shore of [[Hudson Bay]], and along the [[West Coast of the United States|West Coast]] from southern [[California]] to the western shore of [[Alaska]] and the [[Aleutian Islands]]. == Subspecies == * ''G. a. aculeatus'', the '''tiddler''' or '''tittleba'''t, is found in most of the species range, and is the subspecies most strictly termed the three-spined stickleback. * ''G. a. williamsoni'', the '''unarmored threespine stickleback''', is found only in [[North America]]; its recognized range is [[southern California]]. * ''G. a. santaeannae'', the '''Santa Ana stickleback''', is also restricted to