Frilled shark

What it is

The frilled shark is an ancient marine predator resembling an eel in body shape. Its skin ranges from dark brown to grey, and it possesses a long, slender torso measuring up to two metres. The head is broad and flat with a short snout. A distinctive feature is the throat, which displays six pairs of gill slits that form a fleshy fringe. The eyes are horizontal ellipsoids without protective eyelids. The mouth holds three hundred recurved, needle-like teeth arranged in widely spaced rows. Dorsal, pelvic, and anal fins sit near the tail, while the pectoral fins are small and rounded.

Where it lives

This species inhabits the outer continental shelves and upper slopes of the Atlantic and Pacific oceans. In the Atlantic, it ranges from Norway and Scotland south to Morocco and Brazil. In the Pacific, it appears from Japan and Taiwan to New Zealand and California. It typically stays near the ocean floor but migrates vertically to feed at night. While often found between fifty and two hundred metres deep in areas like Suruga Bay, Japan, it can dive deeper than one thousand five hundred metres. It prefers biologically productive waters and avoids depths below one thousand metres in most regions.

How it lives

Frilled sharks hunt cephalopods, particularly squid, along with smaller sharks and bony fish. They use diel vertical migration to reach surface waters at night. To capture prey, they brace their tails against rocks or the seabed, then lunge with flexible jaws. Their wide gape allows them to swallow animals larger than themselves. The teeth snag soft bodies and tentacles effectively. They are generally solitary, though aggregations occur on seamounts during mating. Parasites such as tapeworms and nematodes affect them, and they face predation from larger sharks, evidenced by missing tail tips.

Breeding and life cycle

Reproduction follows an aplacental viviparous strategy. Embryos develop inside egg capsules within the mother’s uterus, feeding on yolk rather than a placenta. Gestation lasts up to three and a half years, resulting in litters of two to fifteen pups. There is no distinct breeding season. The long development period ensures young are born relatively large and capable of surviving in deep-water environments immediately after emerging from their capsules.

Fish and people

Commercial fisheries occasionally catch frilled sharks as bycatch in deep-sea trawls. The meat is utilized for human consumption or processed into fishmeal, giving the species some economic value. Despite being caught at significant depths, occurrences below twelve hundred metres remain uncommon. Fishing pressure has not led to immediate conservation crises, but data on population trends remains limited due to their remote habitat and elusive nature.

Status and threats

The International Union for Conservation of Nature does not list a specific status year in the provided text, but the species is generally considered Least Concern due to its wide distribution. However, its slow reproductive rate and long gestation make populations vulnerable to overfishing. Threats include commercial bycatch and potential habitat disruption from deep-sea mining. Protection measures are currently minimal, relying largely on existing fisheries regulations in various countries.

Relatives and look-alikes

The southern African frilled shark (Chlamydoselachus africana) is the only other extant species in the family Chlamydoselachidae. It differs anatomically with shorter gill slits and fewer vertebrae. Historically, scientists debated its relation to extinct cladodont sharks or hybodonts. Modern genetics places it within the order Hexanchiformes, alongside cow sharks. Fossil records suggest ancestors lived in shallow inland waters before retreating to deep seas following competition from other shark groups.

Questions people ask about Frilled shark

Good reading and sources

• Frilled shark on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data