The filmed specimen, a female, was not alone. Attached to his ventral side is his little “husband” – a male who carries the parasitic existence fixed on the female’s abdomen, giving her the semen necessary for reproduction and receiving in return the nutrients necessary for life directly from the blood flow of the “wife”. , informs Live Science.
German biologists Kirsten and Joachim Jakobsen filmed this extraordinary scene with the help of cameras from the Lula 1000 submarine, which sank off the coast of the island of Sao Jorge in the Azores archipelago, 1,360 kilometers west of Portugal.
Until now, researchers have never been able to see a living specimen in the wild in this species of fish (Caulophryne jordani).
The recording lasting 25 minutes was made at a depth of 800 meters.
A premiere from the depths
“It’s something unique, observed for the first time,” said Ted Pietsch, professor emeritus of aquatic sciences and curator of the Department of Marine Vertebrates at the Burke Museum of Natural History and Culture at the University of Washington.
Biologists have cataloged about 160 species of deep-sea fish in the planet’s oceans, but opportunities to observe them in the wild are extremely rare. In the case of this fish species, there are only 14 specimens preserved in formalin in various museums and universities around the world, and the male C. jordani has never been seen before.
Flyfish are famous for their bioluminescent fishing gear – one or more “rods” that start from the fish’s head and are used to draw prey closer to its sharp-toothed mouth.
These fish live at depths between 300 and 5,000 meters and they can even swallow prey larger than their own body because they have a stomach and extensible jaws.
A unique partnership
Females and males of this species of anglerfish are extremely different. Females are about 60 times larger than males and 500,000 times heavier.
Males do not have the bioluminescent “fishing rods” with which females fish, because they do not need to feed themselves. Males have disproportionately large eyes and nostrils, which allows them to find their mate in the dark depths. Once the female is found, a male begins a lifelong partnership with her.
When a male finds a female, he is bitten by her abdomen, and his circulatory system and tissues fuse with those of the female. The two thus continue their lives in a symbiotic relationship. The male provides fertilization and, instead, feeds directly on nutrients from the female’s blood.
This behavior is impossible to capture in an aquarium. These abyssal fish cannot survive the low pressure of the ocean surface.
C. jordani fish rods move independently of each other, being activated by their own muscles and nerves. “These bioluminescent ‘rods’ generate a kind of network of tactile antennae around the fish – similar to feline whiskers – with which they monitor the approach of prey or predators,” explains Ted Pietsch.
The light emitted by the fish along its “antennae” serves to attract prey from the abysmal darkness, but it could also have other roles – such as deterring potential predators by making the fish look bigger than it really is.
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