Deep-sea anglerfishes look quite spectacular – and a little scary. Their mating behavior is also unusual and unique in the animal kingdom. In the most extreme cases, deep-sea anglerfish females may be more than 60 times the length and about half-a-million times as heavy as the males. Tiny dwarfed males become temporarily or permanently attached to relatively gigantic females, fuse their tissues, and then establish a common blood circulation.
The male becomes entirely dependent on the female for nutrient supply, like a developing fetus in the womb of a mother or a donated organ in a transplant patient – a process called ‘sexual parasitism’. In return, the male delivers sperm to fertilize the eggs. This form of sexual parasitism is unique in the an