Exclusive: ‘I’ve never seen anything like it.’ Video of mating deep-sea anglerfish stuns biologists

C. jordani’s light show was also a stunner. Like other deep-sea anglerfish, the female has a bioluminescent, lurelike appendage that drifts in front of her head to attract prey. But in the video, the filaments and fin rays also appear to emit light at their tips and at intervals along their length—something that’s never been seen before. Pietsch suspects that the light is bioluminescent—meaning, it’s produced within the animal itself—but he notes that it’s hard to know whether the structures are reflecting light from the submersible or are actually glowing.

The tiny male is also a key part of the discovery. Like many other species of anglerfish, C. jordani forms a permanent pair bond—once a male finds a mate, he bites into her, eventually fusing with her tissue and gaining sustenance through her blood stream. Scientists have known about this bizarre reproductive strategy because they’ve seen dead males latched onto dead females, but people have never seen it in the wild—until now.