Finding a mate isn’t easy in the inky depths, so female anglerfish have learned to keep them once they catch them. The comparatively tiny male (seen below the female’s tail) latches onto his mate, essentially becoming an appendage. He feeds directly from her circulatory system in exchange for fertilizing her eggs. Females may sustain several males at the same time. AVERAGE SIZE: Female—5 inches (13 centimeters); Male—1 inch (2.8 centimeters).