Sevengill

Sevengill sharks are a group of sharks belonging to the family Hexanchidae. The name "sevengill" refers to the number of gill slits they possess, which is unusual as most sharks have five or six pairs. There are currently four recognized species within the family: the bluntnose sevengill (Notorynchus cepedianus), the sharpnose sevengill (Heptranchias perlo), the Pacific sevengill (Notorynchus platycephalus), and the sixgill cowshark (Hexanchus griseus) which, despite its name, can also have seven gill slits in some individuals.

These sharks are found in temperate and tropical waters worldwide, inhabiting both deep-sea environments and coastal areas. They are generally considered to be slow-moving but are opportunistic predators, feeding on a variety of prey including fish, cephalopods, crustaceans, and carrion. Sevengill sharks are ovoviviparous, meaning their eggs hatch inside the mother.

The bluntnose sevengill is perhaps the most well-known species and is often found in shallow, inshore waters, which can lead to interactions with humans. While generally not considered aggressive, they can bite if provoked or mistaken for prey. Their distinctive appearance, with their seven gill slits and often large size, makes them a notable member of the shark population in the areas they inhabit. Research into sevengill shark biology and behavior is ongoing to better understand their ecological role and conservation status.