Scientists Reveal Extraordinary Mating Behaviour of Deep-Sea Anglerfish
Scientists have shed more light on the remarkable mating behaviour of deep-sea anglerfish, a species in which the male permanently fuses with the female in one of nature’s most unusual reproductive strategies.
Living in the dark depths of the ocean, the much smaller male anglerfish attaches itself to a larger female by biting into her body. Over time, their skin and blood vessels merge, allowing the male to survive by drawing nutrients directly from the female’s bloodstream.
As the fusion progresses, many of the male’s organs gradually shrink and lose their function, leaving him permanently attached to the female as a reproductive partner.
Researchers have documented female anglerfish carrying as many as eight fused males simultaneously.
For years, scientists questioned why the female’s immune system does not reject the attached male in the same way it would reject a foreign organ or tissue.
A study published in Science in 2020 by researchers from the Max Planck Institute of Immunobiology and Epigenetics found that anglerfish lack key immune system genes responsible for identifying and rejecting foreign tissue.
According to the researchers, the absence of these immune genes allows the male and female to fuse without triggering an immune response, making the anglerfish the only known animal in which two separate individuals permanently merge into a single functioning organism for reproduction.
Scientists say the unique adaptation evolved to increase reproductive success in the deep sea, where encounters between males and females are extremely rare due to the vastness and darkness of the ocean.
Scientists Reveal Extraordinary Mating Behaviour of Deep-Sea Anglerfish