Kristen and Joachim Jakobsen – a husband and wife team of deep sea explorers – have captured on video a mating pair of angler fish at 800 m in a specialized submersible craft. They spotted the creatures by chance whilst returning from a five-hour long dive, and carefully followed them in the sub, filming through the craft’s 1.4 m window. This was no mean feat, considering their small size (the larger female is only 16 cm in length) and the pitch darkness of the water at that depth.
The footage is important because up to now scientists interested in angler fish have been largely forced to depend on dead specimens in museums or nets for study. However, this video of a living pair has amazed them by revealing aspects of the fish which can’t be observed in dead animals. For example, the female is shown to suspend herself in a three-dimensional mesh of filaments which, like a cat’s whiskers, allow her to sense her prey; even in complete darkness. These filaments, along with the rays on her fins, also appear to glow like the famous lure on her head, suggesting that they may also be bio luminescent. Finally, the footage also shows the male angler fish, who attaches to his mate by burrowing into her skin and feeding on her blood. This is a permanent, parasitic arrangement which has been known about for some years, but what surprised biologists was the “flexibility” that the male exhibits. He seems able to move in any direction he chooses, despite solidly anchored to his partner. “I would never have guessed that from a [Museum] specimen” says Bruce Robinson, a deep-sea ecologist at the Monterey Bay Aquarium Research Institute, California.
The footage was taken in 2016, but this is the first time it has been released to the public. If you’d like to check it out yourself, here’s a link – https://youtu.be/anDIlMVgNwk