Ghost sharks, also known as chimaeras, are deep-sea dwelling fish that have captured human imagination due to their unusual appearance and elusive nature. The name suggests a frightening predator, but the definitive truth is that these animals are not a danger to people in their natural habitat. Their moniker reflects their otherworldly look and the dark depths where they live, not aggression or threat to humans. The few instances of human injury related to these fish are purely defensive and occur only when a person handles them directly.
Defining the Ghost Shark: Chimaeras of the Deep
Ghost sharks are not true sharks, but they belong to the same class of cartilaginous fish, Chondrichthyes, in the order Chimaeriformes. This group diverged from the ancestors of modern sharks and rays nearly 400 million years ago, making them some of the oldest fish species in the ocean. They are often called ratfish, spookfish, or rabbit fish due to their large, reflective eyes, long tapering tails, and sometimes bulbous snouts.
These fish possess unique anatomical features that distinguish them from sharks. They have only one gill opening on each side of the head, covered by a fleshy flap. Their skin is smooth, lacking the rough denticles found on true sharks. They propel themselves using large, wing-like pectoral fins rather than their tail. Instead of rows of replaceable teeth, ghost sharks have three pairs of mineralized tooth plates designed for crushing prey.
Their natural environment is the deep ocean, typically inhabiting the benthic zone, or seafloor, at depths ranging from 200 meters down to 2,600 meters. This profound isolation is the primary reason why encounters with humans are extraordinarily rare. Their large eyes contain a reflective layer to help them absorb the scant light available in the darkness.
Assessing the Threat to Humans
The vast majority of these fish live far below the depths accessible to recreational divers and are rarely seen near coastal areas. Their moderate size, with many species reaching a maximum length of around 60 to 150 centimeters, also means they are not large predators.
Ghost sharks are bottom-dwelling scavengers and specialized feeders. They primarily consume small benthic invertebrates such as clams, mollusks, worms, and crustaceans. They use sensory organs on their snouts to detect weak electrical fields and movement, allowing them to locate prey buried in the sand or mud.
The only way humans typically interact with a ghost shark is when the fish is accidentally caught as “bycatch” in deep-sea commercial trawling nets. Their primary defense is to flee from larger animals, as they are not built to prey on large mammals.
The Ghost Shark’s Real Defense Mechanism
While ghost sharks are not aggressive, they possess a highly effective, specialized defense mechanism that can cause injury if mishandled. Located just in front of their primary dorsal fin is a single, sharp spine. This spine is not an offensive weapon used for hunting but is instead a passive defense against their own predators, which include larger sharks.
In many species, this dorsal spine is associated with a venom gland. The venom is delivered when the spine penetrates an attacker, inflicting a painful wound. This defensive injury is typically characterized by intense local pain, which can be excruciating for a human, but the venom is not considered lethal.
Injuries to humans occur when fishermen or researchers attempt to remove the fish from a net or handle it without caution. The spine is a passive delivery system, meaning the fish does not actively strike with it. The danger is solely the risk of an accidental, defensive sting.