The planet earth is full of endless life, both in the air, on land and water, which accommodates a huge variety of creatures that allow the balloon has so much activity and beauty. A clear demonstration of diversity of marine life, which is the most development processes have had, so much so that there were born the first vertebrate creatures, ie fish, which has made the variety of fish in the world is huge, so much so that represents about half of the species of the family of vertebrates, thus speaking of the fish referred to a very wide and varied that shows the great biodiversity on the globe. As you can understand fish life represent a very significant group in regard to the species on the planet, so it is interesting to know a little more of the conditions that accompany them. As mentioned earlier the fish are vertebrates, but unlike most vertebrates, the tetrapods ie, not land and no legs, which replace with fins that act as if limbs for movement, your breathing is also very different, since the process is carried out through the gills, which get the oxygen dissolved in water. Locomotion and movement made by fish, is an example of hydrodynamics, since the fish do lateral movements of their bodies, which have the support of the fins. Particular thing that occurs when speaking of fish, is that as a very heterogeneous group of different samples of fish vary widely and have almost no similarity in its image, a clear example of this is the comparison that can be obtained from a great white shark unlike a tuna, in addition to this within the group of fish you can find many species that certain conditions are very special and even rare, as is the case with deep-sea fish, which at marine depths exceeding found 1000 meters where there is no light, through internal processes produce a certain type of lighting, its image is also something monstrous compared to other types of fish, which shows the great variety of fish that has been generated for its extensive presence in the history of evolution. The fish can be found in most forms of water and occur in fresh waters, ie in different rivers and lakes, but they are also located in marine waters could be expressed in all conditions, whether the waters of the polar oceans in tropical areas, deep sea, everything that makes the fish talk about refers to a large group of living things in many ways that offer great diversity and beauty to life in planet.