In the deep ocean, some anglerfish species have evolved one of nature's strangest mating systems. When a tiny male anglerfish finds a female in the pitch-black depths, he bites onto her body and doesn't let go. Over time, his mouth fuses to her skin, their blood vessels connect, and his body gradually degenerates until he becomes little more than a pair of gonads permanently attached to her. The male loses his eyes, fins, and most organs, surviving entirely by absorbing nutrients from the female's bloodstream. In exchange, he provides sperm whenever she needs to reproduce. Some females end up with multiple males fused to their bodies at once, creating a bizarre biological unit that functions as a single organism. This extreme adaptation exists because food is so scarce in the abyssal zone that finding a mate twice is nearly impossible. Rather than risk never reproducing, males have essentially committed to their partner for life by becoming part of her body. The arrangement works, though it's hard to imagine a more unsettling solution to the challenge of deep-sea dating.