The frilled shark: a prehistoric predator with a three-year pregnancy and 300 teeth

Nature · Published 3 October 2026 Swipe more like this →

In short: Often called a living fossil, the frilled shark is a mysterious deep-sea dweller that has survived since the Cretaceous period. With an eel-like body and 300 needle-like teeth, this elusive predator spends its life in the dark, occasionally rising to the surface to hunt in the dead of night.

The frilled shark, Chlamydoselachus anguineus, is a biological anomaly that challenges our understanding of shark evolution. Named for the fringed appearance of its six gill slits, this creature possesses a primitive anatomy, including a cartilaginous notochord and jaws that articulate directly to the cranium. These features led early researchers like Samuel Garman to link the species to ancient, extinct lineages from the Devonian period. While modern genetic analysis suggests it belongs to the order Hexanchiformes, its unique morphology remains a subject of intense scientific interest.

Life for a frilled shark is defined by extreme patience and specialized survival strategies. These sharks are aplacental viviparous, meaning embryos develop inside egg capsules within the mother, feeding on yolk until birth. This process is exceptionally slow; gestation can last up to 3.5 years, one of the longest in the animal kingdom. When they finally emerge, the pups are already 40–60 cm long. Despite their fearsome appearance, their bite is relatively weak, relying on a rapid-strike mechanism and a wide gape to swallow prey whole, including cephalopods and other sharks.

Though they inhabit the outer continental shelf and upper continental slope, these sharks are rarely seen by humans. They are solitary, deep-water residents, though they perform diel vertical migrations to feed near the surface at night. Their habitat is vast, spanning the Atlantic and Pacific oceans, yet they are uncommon below 1,200 meters. Today, they face pressure from commercial fishing, where they are frequently caught as bycatch. While the IUCN has shifted its classification regarding their extinction risk, their naturally uncommon status and slow reproductive rate make them a vulnerable, albeit fascinating, relic of the primeval seas.

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