The frilled shark is a deep-sea creature whose existence often sparks curiosity, largely because its appearance seems to belong to a bygone era. For those seeking current information, the answer is definitive: the frilled shark is still very much alive and swimming in the world’s oceans. Its bizarre, almost mythical appearance has led to speculation and confusion, especially given how rarely it is observed in its natural habitat. This ancient animal represents one of the ocean’s most compelling biological mysteries, surviving in the cold, dark depths far from human sight.
The Living Fossil Status and Confirmation
The frilled shark, formally known as Chlamydoselachus anguineus, holds a rare designation as a “living fossil,” a term used for organisms that have retained primitive characteristics over vast geological timescales. Its lineage can be traced back to the Late Cretaceous period, suggesting that its fundamental body plan has remained largely unchanged for approximately 80 to 95 million years. This remarkable evolutionary stability gives scientists a unique window into the anatomy of prehistoric sharks.
Confirmation of its continued existence is based on modern scientific observation. While it is rarely encountered, the frilled shark is occasionally brought to the surface as unintentional bycatch by deep-sea trawlers operating on the continental shelf. Scientific deep-sea footage and remotely operated vehicles (ROVs) have also provided visual confirmation of the species in its deep-water environment.
A notable example occurred in 2007 when a live female specimen was caught near the surface off the coast of Japan. The species is recognized by the International Union for Conservation of Nature (IUCN) as extant, confirming that this ancient shark is a current resident of the world’s deep oceans. Scientific classification places it in the order Hexanchiformes, which contains other primitive sharks.
Unique Physical Characteristics
The frilled shark’s appearance is markedly different from the streamlined sharks familiar to most people, possessing a long, dark brown or gray body that is notably eel-like in shape. It can reach lengths of up to 6.6 feet (2 meters), and its body lacks the typical robust build of most shallow-water sharks. The head is broad and somewhat flattened, giving it a lizard-like or snake-like look.
The feature that gives the shark its common name is the six pairs of gill slits, which have a distinctive, ruffled or “frilly” margin. The first pair of gill slits extends across the throat, connecting beneath the jaw to form a characteristic collar-like structure. Unlike most modern sharks that have only five gill slits, this six-gill count is a primitive trait.
Specialized Teeth
The jaw structure and teeth are highly specialized for its deep-sea diet. Its mouth is lined with up to 300 needle-sharp teeth, each possessing three cusps, arranged in multiple rows. These teeth are distinctly backward-pointing, an adaptation that makes it nearly impossible for a captured, slippery prey item to escape once inside the mouth.
Habitat and Global Range
The frilled shark’s elusiveness is directly tied to its preferred living environment, which consists of the cold, dark waters of the outer continental shelf and upper continental slope. It typically inhabits the bathypelagic zone, with most sightings occurring between 390 and 4,200 feet (120 and 1,280 meters) below the surface, though individuals have been found deeper. This extreme depth explains why encounters with humans are so rare and why the species remains poorly studied.
The species has a wide, yet patchy, global distribution, found in both the Atlantic and Pacific Oceans. In the western Pacific, populations are known off the coasts of Japan, Australia, and New Zealand. Atlantic sightings have occurred from northern Norway down to parts of Namibia and at various points along the Mid-Atlantic Ridge.
Its deep-water preference is consistent across its range, with the shark generally staying near the ocean floor in biologically productive areas. While some localized populations, such as those in Suruga Bay, Japan, may occasionally be found in shallower waters, this is typically at depths still well below the surface.
Hunting Behavior and Diet
The frilled shark’s unique anatomy translates into a specialized method of hunting in the low-light environment of the deep ocean. It is believed to be an ambush predator, relying on its serpentine body and large mouth to secure prey rather than speed. The shark likely holds its body in a coiled position, waiting to lunge forward like a snake to engulf its unsuspecting target.
This hypothesized snake-like lunging is perfectly suited to the shark’s flexible jaw structure, which allows it to open its mouth extremely wide. The three-pronged, recurved teeth act like a living snare, ensuring that once a slippery target is grasped, it cannot slide out.
The diet consists primarily of cephalopods, particularly squid, which can make up a significant portion of its meals. Analysis of stomach contents from captured specimens also indicates a diet that includes smaller deep-sea bony fish and even other small sharks. The ability to swallow prey whole allows the frilled shark to maximize the caloric intake from any meal it successfully captures.