Commerson's Dolphins.Unusual and in vias of extición. The tonina overa or dolphin tweet (Commerson's dolphin), also called Commerson's dolphin is a species of toothed whale whale of the Delphinidae family that lives in waters of the Southern Hemisphere.
This species was first described by naturalist Philibert Commerson, part of the expedition of Baron de Bougainville around the world; Later, bottlenose dolphins were studied by the expert Francisco P. Moreno.
The species is distributed in two places. The largest population is found in several inlets of the coast of Argentina, in the Strait of Magellan and near the Falkland Islands.
The second population, discovered in 1950, lies near the Kerguelen Islands 4,300 miles east of the first population. They prefer shallow waters. The global population is unknown, but it is accepted that the species is locally common. A inspeccción in 1984 estimated that there were 3,400 specimens in the Strait of Magellan.
In no larger than 57 in. The males do not exceed 106 lbs, while the females are slightly larger, reaching 110 lbs. The head, pectoral fins, genital area, the back of the insertion of the dorsal fin to include in full the caudal fin are black, while the rest of the animal including the throat is white.
The newborn fledgling measure approximately 28 inches in length, are brownish gray or completely gray. During the first year of life will act under the guidance of the mother.
The dorsal fin Commerson's Dolphins is situated immediately behind the middle of the back, meanwhile caudal fin is wide relative to body size, having a central slit approximately 1 in of depth.
Commerson's dolphin is a very active dolphin. It is often observed swimming fast in the water surface and jumping over water. It also runs twists and somersaults, and you can surf on the surf near the beach.
In 2008 the species was listed on the IUCN Red List as "data deficient", for lack of information on population size, trend and threats. There is reason to believe that at least subspecies of South America, are experiencing a decline in parts of its range. However, more research is required to establish the structure of the population in Argentina and human-induced mortality.