Fish differ by having certain characteristics characteristic of the environment in which they live. For this reason we can find freshwater fish, saltwater fish, tropical fish, coldwater fish, among the main groups. Its classification refers to some physical characteristics.
They can be classified into three large groups within the different types de peces are: bony fish, cyclostomous fish (jawless fish) and chondrichthyan fish, which are those types de peces cartilaginous.
Within bony fish there is a great variety, and its main characteristic is that its skeleton is ossified, as we can see in the hippocampus or in seaweed fish. They have a mouth positioned at the end of their head and as for the fins we must say that they vary a lot, although most of them are completely atrophied. They are carnivores and feed on mollusks and crustaceans.
The cyclostome fish They are jawless specimens within vertebrates whose main groups are the lampreys, better known as the sea lamprey, which inserts itself into the body of other fish to scrape their meat and suck their blood and the hagfish These produce large quantities of thick mucus, capable of tying into knots around the bodies. de peces Large size. They are characterized by a serrated, funnel-shaped mouth and teeth.
The cartilaginous fish They have the characteristic of having a cartilage skeleton and generally most species have very sharp scales that can give the impression that they are teeth. Within this group we find sharks and rays, since we speak of one of the most predatory marine species that exist.
All cartilaginous fish are carnivores and most species feed on live prey, although some species feed on the remains of dead animals.