Watch: Deep-sea Anglerfish Mate in Bizarre, Parasitic Ritual Caught on Video for the First Time

A video has captured the mating ritual of the bizarre Fanfin Seadevil anglerfish for the first time ever.

The elusive fish are some of the deep sea's most mysterious inhabitants. Anglerfish are found around the world but are rarely seen in their natural environments. Only a handful of this particular species - all female - are preserved in collections around the globe.

The male of the species had never been observed before. Now one is a movie star.

Researchers Kirsten and Joachim Jakobson captured the film from a submersible craft 870 yards deep in the North Atlantic Ocean, operated by the Rebikoff-Niggeler Foundation.

The footage shows a female anglerfish the size of a fist mating with a tiny male. The male has bitten the body of the female, and their circulatory systems and tissues have fused. From this moment they've functioned as a single organism—he recieves her nutrients and fertilises her eggs—a lifelong sexual parasite.

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"This is a unique and never-before-seen thing," said Ted Pietsch, a University of Washington professor who is an expert on anglerfishes, in a statement. "It's so wonderful to have a clear window on something only imagined before this."

According to Pietsch, this is one of only a few videos depicting the behavior of this mysterious fish. Most of scientist's anglerfish knowledge comes from studies of dead fish.

Anglerfish certainly aren't the prettiest fish in the sea, but they are accesorized with a glowing lurelike apparatus.

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A screenshot of the Fanfin Seadevil mating behavior from the video. Rebikoff-Niggeler Foundation

The fishes' finrays and and long floating filaments, scientists now know, can also produce a tremendous light show. The fish might use these sprawling lights, Pietsch says, to trick predators into thinking theyre much bigger than they are, or that they're a dangerous jellyfish. The lights might also attract prey for the fish itself.

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The video also illuminates structures not recorded in any other fish. Most fish's fins move as a single unit, but the Fanfin Seadevil's finrays are equipped with dedicated muscles that can move independently.

According to Antje Boetius, a biological oceanographer at the Alfred Wegener Institute in Germany, the video "brilliantly shows the otherness of deep-sea life."

It shows "how important it is to observe these animals in their own realm, to understand their behavior and adaptation," she said in the statement.