Anglerfish are weird and mysterious creatures. They live hundreds of metres below sea level, and we have very few specimens of these bizarre animals. Even fewer have been seen alive in the deep ocean they inhabit.
But a new video released through Science Magazine shows not just one, but two anglerfish, in the 'close' mating arrangement these creatures are known for.
For a quick biology lesson, some species of anglerfish have very extreme cases of sexual dimorphism – in this case meaning the male is much smaller than the female.
But besides that, the male also gets quite clingy to the female at mating time, biting into her skin and releasing an enzyme that fuses the two of them together.
After this fusion, the male becomes completely dependent on the female, with the female providing nutrients in exchange for its sperm.
Even more interestingly, in some fish there can be multiple males incorporated into a single female, with some species having up to eight males per female.
But despite how exciting and weird these creatures are, there's only a handful of videos, and never one of a mating pair… until now.
You can see the stunning video below:
The anglerfish pair in the video, Caulophryne jordani, or the fanfin angler, was captured by deep-sea explorers Kirsten and Joachim Jakobsen in a specially designed submersible.
The two explorers were diving off São Jorge Island, when after five hours of searching, they discovered the pair at 800 metres below sea level.
At 16 centimetres (6 inches) long, the female was difficult to capture footage of, especially with the long glowing filaments surrounding the animal.
Although we can't know for sure from the video, the filaments, or the long floating appendages, do appear to be glowing, which would make this discovery another first.
After the Jakobsens returned to land, they sent the video footage to Ted Pietsch, a deep-sea fish researcher at the University of Washington in Seattle.
"I've been studying these [animals] for most of my life and I've never seen anything like it," he told Science Magazine.
"It was really a shocker for me."
Pietsch identified the species as C. jordani, and since the footage has been released, it's given scientists the ability to find out more about these elusive angler fish - for example, showing how maneuverable the male remains despite his fusion to the female.
It's kind of amazing to think about how little we still know about many of the strange and beautiful animals on our own planet.
If you want to find out even more about anglerfish, check out this other great video by the Natural History Museum below.