Deep down in the ocean where no sunlight could reach, animals live a dark life. Among them, the anglerfish stands out not only because of its ghastly looks – gnarly teeth, huge mouth, and the dangling luminous lure on its head but also because of its horrifying parasitic mating process.

There are only a few studies on these mysterious creatures due to the intense environment they live in. Records on how anglerfish reproduce remained in the mist until last century when the first female anglerfish with two tiny fish attached to its belly had been dissected. Only after that, scientists realized that the tiny fish they had mistook for the babies were, in fact, the male fish.

The male anglerfish appear to be extremely fragile compared to the females. They are usually only a fraction of the size of their mates and have no sharp teeth or lures.

While the female anglerfish use their bioluminescent lure to attract other fish and devour their prey with toothy mouths, their male counterparts have extremely sensitive eyes and nostrils which help them to detect the chemicals that female anglerfish release.

Once a male anglerfish finds its mate, it bites into the female's belly and latches on until their bodies fuse. Their skins and blood vessels join together and eventually, the two fish become one.

The gothic romance of the anglerfish allows the male to take all the nutrients it needs from its mate/host. The male's useless body parts such as eyes, fins and some other internal organs gradually degenerate until it is nothing more than a lump of flesh that hangs from the female and provides sperm.

However, not all anglerfish have extreme size differences or adopt a parasitic mating method. In many suborders of anglerfish, the males can hunt by themselves and swim independently throughout their lives. It is only necessary for some deep-sea species that rarely run into others in the abyss to follow this bizarre ritual in order to keep their mates around. Sometimes there could be up to eight males attached to one female.