#23: Deep-Sea Mating
Some of the creatures found in the deep, dark depths of the ocean, like anglerfish, have truly bizarre behaviors. Anglerfish males are minuscule compared to their female counterparts, often dwarfed by a factor of hundreds or even thousands. When a male encounters a female, he latches onto her using specialized mouthparts. Over time, the male’s body fuses with the female’s, becoming essentially a permanent, parasitic attachment.

The male’s tissues merge with the female’s bloodstream, and he loses many of his original organs, retaining only those necessary for reproduction. This obscure form of sexual dimorphism ensures that when the female is ready to reproduce, she has a mate readily available.