The angler fish most people know looks like a Tim Burton concoction of huge uneven fangs, a bulbous brown body and a dorsal spine that dangles over the head to lure unsuspecting victims. This description only applies to the female half of the species. The male is actually a fraction of the size and greatly differs from the female.
The male finds the female and then bites down hard on her side with his sharp little teeth.
According to an article in National Geographic, more than 200 species of angler fish exist, and the majority of them reside toward the bottom of the Atlantic and Antarctic oceans.
Considering the expanse of these two oceans, seeing another angler fish, especially of the opposite sex, is a rare opportunity.
So rare that the angler fish is not going to simply allow the female to swim away. The male finds the female and then bites down hard on her side with his sharp little teeth.
Over time, he physically fuses to her body, losing his eyes and all his internal organs except for the testes. The female can have up to about six males latched to her.