Deep sea anglerfish, Melanocetus Johnsoni, are found in the most inhospitable place on the planet; the cold, dark bottom of the sea. There are over 200 species of Anglerfish, each differing in terms of body structures and size.
However, their most common and distinctive feature is a slender, antenna-like projection extending from its head or mouth, known as a dorsal spine. The spine supports a light-producing organ called a photophore, which acts like a “fishing-rod” as prey are attracted to the luminescent bubble.
Here are some examples of the various species of Anglerfish
However, what is most interesting about deep sea Anglerfish is not just their grotesque appearance and their preying manner, but even more so their mating behavior. The role of males in deep sea Anglerfish is completely reduced. Being barely 1/10th of the size of a female, the male anglerfish live as parasites on females.
A female Anglerfish
From the moment of birth, male anglerfishes seem to have no other role than to search out a female. The tiny male has no bioluminescent lure, instead, they have larger eyes presumably for spotting the flashing lure of the female and a greater olfactory organ (organ of smell, or nose) above its eyes. The reasons behind these physical differences between the sexes could be because in the vast ocean, sexual pheromones are highly essential in locating a mate. Thus, in the dark and vast ocean, heightened sensitivity to the female pheromones is crucial in the reproductive lifestyle of the Anglerfishes.
The Male Anglerfish
Upon locating a female anglerfish, the puny male attaches itself to her body by biting into her. His teeth and jaw then recedes and a chemical is released which fuses the skin and blood systems of both parties. Thereafter, it becomes entirely dependent on the female for its nutrients and oxygen, similar to that of a parasite. In time, the male anglerfish’s eyes and other digestive organs regresses and its body degenerates into essentially a pair of sperm producing testicles.
At this juncture, the female essentially becomes a hermaphrodite, with up to 6 of these male parasites attached to various parts of her body. As a functional hermaphrodite, the female is able to have fertilize her eggs from the moment she releases them from her body.
example of female Anglerfish with attached male parasites
However this is not all, even more intriguing in fact is that the female anglerfish can carry as many as 6 of these parasitic males at one time! thus a single female could have six pairs of testicles at her beck and call, supplying her with a fresh supply of sperms at any point in time!
Here is a video of the strange mating behavior of deep sea anglerfish
Perun, Blane. (1999) “Deep Sea Angler Fish”
Nationalgeographic.com (1996-2010) “Anglerfish”
“Angler Fish Mating Customs” by howtofaint. Youtube Channel, 7 april 2009