Sharks often spark questions about their potential danger. Among diverse species, the seven-gill shark frequently raises curiosity regarding its interactions with humans. This article explores the nature of seven-gill sharks to understand whether they pose a significant threat.
Meet the Seven-Gill Shark
The seven-gill shark, also known by names such as the broadnose sevengill shark or cow shark, stands out physically from most other shark species. While most sharks possess five gill slits, the seven-gill shark uniquely features seven pairs of gill slits. It has a thick body, a broad head with a blunt snout, and a single dorsal fin positioned far back, closer to its tail. They exhibit counter-shading, with a silver-gray to brown top and a pale underside, often speckled with small black and white spots, which helps them blend into their marine environment.
These sharks can reach impressive sizes, with mature males typically around 4.9 feet (1.5 meters) and females reaching approximately 7.2 feet (2.2 meters), though some individuals have been recorded up to 11 feet (3.3 meters) in length and weighing over 400 pounds (182 kg). Seven-gill sharks inhabit temperate waters across the globe, found in coastal areas, bays, estuaries, and even deeper offshore environments up to 1,870 feet (570 meters). As opportunistic predators, their diet is varied, including other sharks, rays, bony fishes, and marine mammals.
Analyzing Documented Encounters
The question of whether seven-gill sharks are dangerous to humans is best addressed by examining documented encounters. The International Shark Attack File (ISAF) indicates a low number of unprovoked attacks attributed to seven-gill sharks, with only five recorded globally since the 16th century, none of which were fatal. Most recorded interactions that result in a bite are provoked, often occurring when sharks are caught by fishers, approached too closely by divers, or attracted by spearfishing activities.
These sharks are known to be aggressive when provoked, and when caught, they may thrash and snap. Incidents involving divers, such as a sevengill biting a diver’s regulator and head in New Zealand in 2013, are typically linked to situations where the shark felt threatened or was otherwise instigated. While their size and predatory nature mean they are capable of inflicting harm, their general behavior towards humans is not one of active aggression or hunting. The limited number of unprovoked incidents, coupled with the context of provoked events, suggests that they do not pose a frequent or significant threat to humans in their natural habitat.
Understanding Their Natural Behavior
The natural behavior of seven-gill sharks provides insight into their low rate of human encounters. These sharks are primarily nocturnal or crepuscular hunters, meaning they are most active during dawn and dusk. They are opportunistic predators that employ various hunting strategies, including stealth and ambush tactics. While they can exhibit bursts of speed, they typically move slowly near the seafloor.
Seven-gill sharks are thought to engage in social hunting, sometimes forming groups to target larger prey, such as seals or other sharks. Despite their predatory capabilities, they are often described as curious rather than inherently aggressive towards humans. Their preferred habitats, which include coastal bays and estuaries, often serve as nursery grounds for their young. This combination of nocturnal activity, ambush hunting, and general disposition contributes to the rarity of unprovoked attacks.
Safety and Interaction Guidelines
For individuals in marine environments inhabited by seven-gill sharks, particularly divers, adhering to safety guidelines can minimize potential risks. Maintaining a respectful distance is paramount, avoiding any actions that might be perceived as provocative or threatening to the shark. It is advisable to avoid feeding sharks, as this can alter their natural behavior and encourage them to associate humans with food. Divers should also refrain from making sudden movements or excessive splashing, as erratic actions can attract unwanted attention.
Awareness of surroundings, especially in areas known for seven-gill shark presence, is important. Avoiding swimming at dawn or dusk, when these sharks are most active, can also reduce the likelihood of an encounter. If an encounter occurs, remaining calm and making slow, deliberate movements is generally recommended. Exercising caution and following established marine safety practices are prudent when sharing the ocean with large predators.