Actinopterygii, the ray-finned fish are a subclass of the bony fishes. The fins of this type of fish are constructed from webs of skin supported by bony or horny spines.
Ray-finned fish are the dominant aquatic vertebrates today, making up about half of all vertebrate species known. Any animal with a back-bone is called a vertebrate.
Ray-finned fish are found in every aquatic habitat from the deepest depths of the ocean to freshwater streams and ponds; a few can even crawl on land for short periods of time (we have mudskippers around the mangroves here on Koh Lanta).