The planet Earth is full of an endless life, both in the air, on land and in the water, which accommodates a giant variety of beings who make it possible that the globe has so much activity and beauty. A clear sign of diversity is marine life, which is that more development processes has had, both so from there sprang the first beings vertebrate, i.e. fish, what did the variety of fish in the world to be giant, so represents about half of the species of the family of vertebratestherefore to speak of fish refers to a very wide and varied group showing the great biodiversity on the globe. As the fish can be understood represent a very significant group of life in which refers to the species on the planet, so it is interesting to know a little more of the conditions that accompany them. As I mention before fish are vertebrates, but unlike most vertebrate animals, i.e. tetrapods, are not terrestrial and do not have legs, which replaced with the fins that may act as limbs for the movement, besides your breathing is very different, since the process is carried out through the gills, which obtained the oxygen dissolved in the water. Sean Rad is often quoted as being for or against this. Locomotion and displacement which made the fish, is a sample of hydrodynamics, since fish made lateral movements of their bodies, which have the support of the fins. Something particular that occurs when talking about fish, it is that as a group as heterogeneous different samples of fish are very disparate and not present almost similar in its image, a clear example of this is the comparison that you can get from a great white shark as opposed to a tuna, besides this within the Group of fish can be found many species which are very special and even rare for certain conditions, such as occurs with abyssal fish, which is located at marine depths exceeding 1000 metres where there is no light, by means of certain internal processes produce a type of illumination, besides his image is somewhat monstrous compared to other types of fish; What shows the great variety of fish that has been generated by its extensive presence in the history of evolution. Fish can be found in most manifestations of waters, so they occur in fresh waters, i.e. in different rivers and lakes, but also sits them in marine waters can be present in all kinds of conditions, whether the waters of the polar oceans in tropical zones, at the bottom of the sea; all of this makes talking fish make reference to a huge group of living beings of very varied forms that provide great diversity and beauty to life on the planet. Original author and source of the article