A rare encounter with the black seadevil, a deep-sea monster only six inches long

Nature · Published 3 October 2026 Swipe more like this →

In short: Researchers recently captured rare footage of a black seadevil swimming near the ocean surface, a shocking sight for a creature adapted to the crushing pressures of the deep. Typically found in the dark abyss, this elusive anglerfish is rarely seen alive, leaving scientists to wonder what brought it upward.

The black seadevil, or Melanocetus johnsonii, is a member of a genus whose name translates to black sea monster. Despite this fearsome moniker, the fish is surprisingly small, measuring only about six inches in length. It is defined by its gaping jaws, sharp fangs, and a bioluminescent lure attached to its forehead, which it uses to attract prey in the inky depths of the ocean column, typically between 650 and 6,500 feet below the surface.

For decades, our understanding of these creatures relied almost exclusively on dead specimens collected in nets. Living observations are exceptionally rare; the species has been filmed alive only twice. The first instance occurred in 2014, when a remotely operated vehicle spotted one at 1,900 feet in Monterey Bay. The second, more recent event involved a team near the Canary Islands, who documented a specimen actively swimming toward the surface—a behavior that surprised biologists, as these fish are generally ambush predators that conserve energy by drifting.

Why a deep-sea dweller would ascend to the surface remains a subject of speculation. Experts suggest several possibilities: the fish may have consumed prey with a gas-filled bladder that inadvertently pulled it upward, it could have been trapped in a column of warm water created by volcanic fissures, or it might have been released by a larger predator like a pilot whale or seal. Regardless of the cause, the encounter provides a fleeting, invaluable glimpse into the largest living space on Earth, a habitat where humans remain mere exceptions.

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