Coffin Ray

Fascinating facts about the Coffin Ray

• A single jolt from this ray can reach 200 volts, delivering a severe but non-fatal shock to a human; it can issue multiple shocks, with each successive shock weakening over about ten minutes.
• A 60 cm (24 in) individual once swallowed a 70 cm (28 in) flathead, the prey’s tail still sticking out of its mouth, showing how it can tackle fish longer than itself before choking on overly large meals.
• Although most are found in waters shallower than 80 m (260 ft), records show this species as deep as 240 m (790 ft) and a 1910 trawl caught them between 86 and 219 m, highlighting its surprising depth flexibility.
• Females give birth to 4–8 pups each summer; the newborns measure 8–11 cm (3.1–4.3 in), and both sexes reach sexual maturity at 40–48 cm (16–19 in), illustrating a compact life cycle for a bottom-dwelling predator.
• The ray’s scientific name traces back to an 1795 illustration misidentified as a goosefish, and its genus name derives from the Greek “húpnos” meaning “sleep,” a nod to the numbing shock it delivers.

At a glance

About the Coffin Ray

The coffin ray, Hypnos monopterygius, is a small electric ray that inhabits Australian inshore waters shallower than 80 m, though occasional records extend to 240 m. Its pear-shaped body, flabby disc as wide as it is long, and an extremely short tail give it a distinctive coffin-like silhouette that inspired its common name. The skin, free of denticles, ranges from dark brown to reddish, pinkish or yellowish, often plain or sparsely patterned, while the underside remains pale. Two kidney-shaped electric organs flank a large, highly distensible mouth capable of swallowing prey whole; adults typically measure about 40 cm, though individuals up to 70 cm, or even 92 cm, have been reported. By night the ray lies buried in sandy or muddy substrates, exposing only its tiny eyes and spiracles, and when disturbed it can erupt from the sediment, looping with its mouth agape before retreating. A nocturnal ambush predator, the coffin ray feeds mainly on benthic bony fishes, but its diet also includes cephalopods, crustaceans, polychaete worms, and on rare occasions penguins and rats. Its powerful electric discharge, up to 200 volts, stuns prey and deters predators such as tiger sharks, which have been found with dozens of rays in their stomachs. Reproduction is aplacental viviparous; females give birth to litters of four to eight pups in summer, each newborn measuring 8–11 cm. Despite its ability to deliver a severe, non-fatal shock to humans, the ray is not commercially valued and typically survives capture and release, underscoring its resilience in a changing marine landscape.

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