In the video Tawny Nurse Shark is a species of the family ginglymostomatidae shark, and the only extant member of the genus Nebrius; is part of the Family Nurse sharks, they are basically nocturnal, although off Madagascar are active all day. It was filmed up in Malagasy waters about 20 meters deep, it has moved away just perceived the presence of divers. Squalo Nutrice Nurse shark
The Nurse Shark (Ginglymostoma cirratum) is an elasmobranch fish within the family Ginglymostomatidae.
They are directly targeted in some fisheries and considered as bycatch in others. The conservation status of the nurse shark is globally assessed as being data deficient in the IUCN List of Threatened Species owing to the lack of information across its range in the eastern Pacific Ocean and eastern Atlantic Ocean. Squalo Nutrice Nurse shark
They are considered to be a species of least concern in the United States and in the Bahamas, but considered to be near threatened in the western Atlantic Ocean, because of their vulnerable status, in South America and reported threats throughout many areas of Central America and the Caribbean.
Nurse sharks are opportunistic predators that feed primarily on small fish and some invertebrates. They are typically solitary nocturnal animals, rifling through bottom sediments in search of food at night, but often gregarious during the day forming large sedentary groups. Squalo Nutrice Ginglymostoma cirratum
(Extract from Wikipedia)
Sono oltre 4.000 le specie di pesci che abitano le barriere coralline. Le ragioni di questa diversità sono ancora oggetto di approfondimento degli scienziati. Le barriere coralline sane possono produrre fino a 35 tonnellate di pesce per chilometro quadrato ogni anno e quindi sono una importante risorsa, da non sfruttare in modo eccessivo come sta avvenendo, per l’alimentazione umana in particolare per quei popoli che le abitano; è chiaro barriere danneggiate ne producono molto meno.