Carcharhinus obscurus Dusky Shark Tooth Dogfishes Cartilaginous Fishes Chondrichthyes Selachians Elasmobranchs Carcharinidae

Description

Origin : Indian Ocean (Madagascar)

Dusty Shark Tooth Carcharhinus leucas mm 16-20 Dogfishes Cartilaginous Fishes Chondrichthyes Selachians Elasmobranchs Carcharinidae.
Syn. Carcharhinus iranzae, Carcharhinus obscurella, Carcharias macrurus, Eulamia obscura, Galeolamna eblis, Galeolamna greyi, Galeolamna macrurus , Prionodon obvelatus, Squalus obscurus.

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Dusky Shark (Carcharhinus obscurus Lesueur, 1818) is a species of the family Carcharhinidae that lives in tropical and warm temperate waters around the globe.
The specific epithet obscurus is in reference to its color. The various populations of this species migrate seasonally to thousands of kilometers towards the poles toward the equator in summer and in winter. In Italy it was reported in the Sardinian Sea and the Strait of Sicily.
Their habitat is a transition zone with coastal species such as the sandbar shark, pelagic species such as Carcharhinus falciformis and Carcharhinus longimanus, those who live in deep water as the bignose shark and island species such as Carcharhinus albimarginauts and Carcharhinus galapagensis. A fairly detailed study has tried how these animals spend most of their time at depths of 10 and 80 meters, descending occasionally up to 200 meters and exceptionally up to 400 meters deep. These animals prefer temperatures between 19 and 28 degrees Celsius and avoid areas and low salinity such as estuaries.
As one of the larger species of its kind, it can reach a length of 4 meters and a weight of about 350 kg. From his position of apex predator, adults have no significant predators, while young people are mostly captured by bull sharks, tiger sharks, Zambezi sharks and great white sharks.
They have a very varied diet, consisting mainly of bony fish, cartilaginous fish and cephalopods, but also crustaceans, starfish, bryozoans, marine turtles, marine mammals, carrion and garbage.
You find me in the mouth 13-15 (usually 14) rows of teeth on each side. The upper teeth are wide, triangular, slightly oblique and coarsely serrated, while the lower ones are thinner and rights, with indentations thinner. The bite of a brown shark possesses a force of 590 Newton the tip of the single tooth, and this amount corresponds to the largest ever recorded for a shark, even if this shows how the force is concentrated into a restricted area such as that of the tip of the tooth .
The species is viviparous and the reproductive cycle lasts three years. The female gives birth to 3 to 14 pups after a gestation period of 22-24 months and employs an additional year to be ready to become pregnant again. It can also store sperm for a long time, since rarely a suitable coupling pair is encountered, because of the nomadic lifestyle of the species and the inherent small size of populations. The growth of these animals is slow, seen that reach maturity at approximately 20 years. The duration of their life is estimated between 40 and 50 years. Given the low rate of reproduction, the species is exposed and vulnerable to human behavior. It is regarded as a valuable animal for commercial fishing and for their fins, utilized in the production of shark fin soup, which for meat, skin and liver oil. In general, the species is potentially dangerous to humans because of its size, but verified cases of attacks humans are scarce.
Although in general it is difficult to assign to a fossilized tooth Carcharhinus, in the case of brown shark species it is very well represented by numerous finds dating from the Miocene (between 23 and 5.3 million years ago) found in Africa, USA and South America.