requins

Requins are cartilaginous fish known as sharks. They belong to the class Chondrichthyes and the subclass Elasmobranchii. More than 500 species are described. Requins have a skeleton made of cartilage, a streamlined body, multiple gill slits, and dorsal fins. They possess rows of replaceable teeth and highly developed senses, including the ampullae of Lorenzini and acute olfaction.

Distribution and habitat: Requins inhabit oceans worldwide, from shallow coastal waters to deep seas, and a few species enter rivers. They range in size from small species to the whale shark, the largest fish, exceeding 12 meters. They occupy reefs, open waters, and continental shelves.

Diet and reproduction: Most are carnivorous, feeding on fish, marine mammals, and invertebrates; some, like the whale and basking sharks, are filter feeders. Reproduction varies: oviparous (egg-laying), ovoviviparous, and viviparous. Litter sizes and gestation periods vary by species.

Conservation and human interactions: Requins are used for meat, fins, and cartilage; bycatch is common. Overfishing, finning, and habitat loss threaten many species. Several are listed as vulnerable, endangered, or near threatened by the IUCN. Their slow growth and late maturity complicate recovery; protections and targeted research are increasingly common.

Notable species: great white shark (Carcharodon carcharias), tiger shark (Galeocerdo cuvier), hammerhead sharks (Sphyrnidae), and the whale shark (Rhincodon typus).