They are a group of seabirds, not flying, that are distributed almost exclusively in the Southern Hemisphere (except the penguin of the Galapagos Islands, a species of the genus Spheniscus: Spheniscus mendiculus, endemic to the Galapagos Islands, Ecuador).
The first Europeans to observe these birds were members of Vasco da Gama's first expedition, who called them little birds or stupid birds because of their clumsy and upright gait and because they were unable to fly. Years later, when the first British saw These animals were called Penguins, which was the name they gave to some species of the Acidae family, such as the giant North Atlantic. However, despite the apparent similarities resulting from the evolutionary convergence, the Northern Hemisphere's alcas are not related to the Spheniscidae. With the passage of time, it has been imposed to apply the name only to members of the Spheniscidae family
There is controversy regarding the amount of species that currently exist, varying between sixteen and nineteen according to the criteria used, although the number with the greatest consensus is that of seventeen species. These species are divided into six well-defined genera, some of which also include extinct species
Penguins live in the open sea of the Southern Hemisphere; only one species lives on the line of Ecuador in the Galapagos Islands, but this archipelago is included in its entirety in the South Pacific Ocean. They nest on the coasts of Antarctica, New Zealand, South Australia, South Africa, all sub-Antarctic islands, Galapagos Islands (Ecuador), Peru, Chile and Patagonia Argentina. Outside the breeding season, they can be found much further north, regularly reaching southeast Brazil through the Atlantic and wandering to Colombia and Panama through the Pacific. In the inter-tropical regions they are found only in certain areas of cold water currents, as in the west coast of South America with the Humboldt current, in the Galapagos islands with the Cromwell current or in South Africa with the Benguela current . Most species inhabit between 45 and 60 ° south latitude; the largest population is found around Antarctica and in the nearby islands, 4 while the largest population after these places is located in Punta Tombo, Patagonia Argentina, which is home to more than one million Magellanic penguins.
Penguins of the genus Aptenodytes, Megadyptes, Eudyptula and Spheniscus feed mainly on fish. The genus Pygoscelis feeds mainly on plankton. The diet of the genus Eudyptes is very little known, but it is believed that many species feed mainly on plankton. In all cases the diet is complemented by cephalopods or plankton.
All penguins, like other seabirds, have a gland that allows them to eliminate excess salt by ingesting seawater and makes the ingestion of fresh water unnecessary.
Penguins are the only non-flying living birds adapted to wing-propelled diving. Therefore, its wings have become fins with strongly compressed bones and rigid joints that prevent the independent movement of the wing bones. The bones are denser than those of other birds, increasing their resistance to impacts and also increasing the weight of the bird reducing its buoyancy. The legs are located far back on the body, making it difficult to move on land but acting as rudders underwater. The penguins are capable of reaching speeds of up to 60 km / h, although their normal speed ranges between 5 and 10 km / h. The time of immersion increases based on the size of the species, with the emperor (Aptenodytes forsteri) being the one with the longest breathing: about 18 minutes. The main oxygen reserves during these periods are not in the form of pulmonary oxygen, but are found in the muscle that contains high amounts of myoglobin.
