The deep sea is a hard environment to live in for a variety of reasons. Like, for instance, you can’t see anything down there. As sunlight travels through water it gets absorbed and scattered, so the deeper you go into the ocean, the less sunlight you see. By the time you get about 3,300 feet deep in the ocean, all the sunlight has been blocked and everything looks like this:
The darkness of the deep sea creates some challenges for the animals that live there. For one thing, it is a lot harder to find something to eat when you can’t see anything. Also, total darkness makes it really hard to find a boyfriend or girlfriend.
Anglerfish have an interesting way to solve that problem.
Anglerfish are fish that look like this:
The anglerfish in those photos live in the deep sea, where they have to deal with challenge of how do you find a nice anglerfish boy or girl to settle down with when you live in total darkness. Unfortunately, anglerfish do not have online dating sites, or reality TV shows where they compete with a bunch of other anglerfish to marry someone they just met. Instead, they have their own bizarre and kind of disturbing method to find a mate.
When a male anglerfish is born, his number one goal, besides staying alive, is to find a female anglerfish. Since he can’t see anything in the deep sea, boy anglerfish find girl anglerfish using their sense of smell. The girl anglerfish helps the boy anglerfish out by producing a strong-smelling chemical called a pheromone. The boy anglerfish will follow the pheromone odor trail until he finds the girl anglerfish that is stinking up the place. (When you’re a teenager, you may also start releasing stinky pheromones (though you may not), but we as a society (at least in the U.S.) have decided that we don’t want to smell that stuff all the time, so you’re probably going to cover it up with deodorant.)
When boy anglerfish meets girl anglerfish, it is not much like a romantic comedy movie. For one thing, none of the anglerfish work in a bookstore. For another thing, the boy anglerfish looks like a baby fish and the girl anglerfish looks like a giant monster who may be forty times bigger than he is.
Though the girl anglerfish looks like she could easily eat the boy anglerfish, their relationship begins by the tiny boy biting the giant girl. The boy chews into her belly and then holds on until his mouth fuses with her body. Then he stays there the rest of his life and she drags him around everywhere she goes.
As weird as all that sounds, it gets even weirder. The attached male gets connected to the female’s digestive and circulatory system. Since he now gets all the food and blood he needs from her and he doesn’t need to move at all, a bunch of his body parts that he doesn’t use anymore start disappearing, like his eyes, fins and muscles. Eventually he is just this blob hanging off her belly who is living off her like a parasite, except he can occasionally help her out because certain of his boy parts are still around and available whenever she is ready to make eggs.
Sometimes girl anglerfish will have two or three blobby boyfriends attached to their bellies. This weird-sounding thing that anglerfish do is actually an adaptation that allows certain anglerfish (not all anglerfish species do this) to survive as a species in the deep sea. By having a male or more than one male attached to her belly, female anglerfish do not ever have to ever worry about losing their boyfriends and then having to find a new one in the deep, dark sea. Their boyfriends are always with them so the females are guaranteed throughout their adult lives to be able to make eggs and produce new anglerfish whenever they need to.
PS. Make sure to tell your mom that male anglerfish attach to female anglerfish and spend their entire lives living off them like parasites. I guarantee she will think that is funny.
To learn more about anglerfish, read my book A Day in the Deep.
Online References and Resources:
Animals for Smart People YouTube channel. "Anglerfish Mating is Pretty Gross, Guys" video.
Encyclopedia of Life. "Deep-sea Anglerfishes."
Mental Floss. "The Horrors of Anglerfish Mating."
Water Encyclopedia. "Light Transmission in the Ocean."
Why Evolution is True blog. "Sexual parasitism in anglerfish."
Photos and Images:
Click the photos and images used above to find their sources, except for the image of blackness, which is a photo of my pocket taken with my iPhone.