Superficially the frilled shark resembles a dark brown or gray eel, but the six gill slits identify it as a shark. The tissue of the gill slits protrudes somewhat, thus inspiring the common name. Its dorsal fin is small, anal fin large, and the caudal fin (tail fin) is highly asymmetric, the dorsal part almost unnoticeable. Its teeth are small, tricuspid, and very sharp. It has been recorded at up to 2 m in length.

Distribution is worldwide, but they seem to be uncommon across this range. The sharks are usually found at depths of 120 m to 1,400 m. They typically eat other sharks, squid, and bony fish.

Reproduction is not well understood, but like many other sharks they bear live young (ovoviviparous), with litter sizes of 2 to 12 pups. Compagno states "They are pregnant for a long time, probably one to two years". This would give the frilled shark the possibility of having the longest gestation of any vertebrate, even exceeding the elephant's period of 22 months.

Frilled sharks appear regularly in the catches from bottom trawling, and when caught are used as food or for fishmeal.

On January 23, 2007, staff at Awashima Marine Park in Shizuoka, south of Tokyo, were alerted by fishermen to a 1.6m female frilled shark and was videoed & captured by park staff who were concerned that the shark appeared to be unhealthy. The shark died a few hours after capture.