This is marriage folks...Absurd Creature of the Week: The Anglerfish and the Absolute Worst Sex on Earth
Teen movies are, at their core, veiled studies in evolutionary biology, with young men and women coming to sexual maturity and either giving into or resisting what is arguably an animal’s sole purpose on this planet — to find a mate. Some decide to wait until they’re married, others lack the desirable traits to even get that far, and still others succeed and consequently have to put off college for a while.
But if the deep-sea anglerfish happened to have the cognitive and physical capabilities required to produce its own such films, there’d be decidedly fewer plot twists. Every single movie would go a little something like this: Boy meets girl, boy bites girl, boy’s mouth fuses to girl’s body, boy lives the rest of his life attached to girl sharing her blood and supplying her with sperm. Ah, a tale as old as time.
The over 300 extremely varied species of anglerfishes inhabit everything from shallow to super-deep waters, and are so named because they are fish that fish for fish using lures, which are actually highly modified spines of dorsal fins that have migrated to their snouts. But among the 160 deep-sea species, only some 25 engage in the aforementioned biting-fusing-mating, what is known as sexual parasitism. In this group, the diminutive male looks like an entirely different species, lacking the female’s enormous jaws and characteristic lure.
And with two dozen other species of anglerfishes that engage in this manner of reproduction, the male had better be damn sure he chooses the right one. Luckily, the female puts on the red blue light — in the form of glowing bacteria living in her lure. Incredibly, some 90 percent of species in the deep utilize such bioluminescence.
“The bait out there is not only an organ of luminescence, but structurally it’s species-specific,” said Pietsch. “Every species of these 160 forms within this group, they have a pattern of filaments, and pigment patterns, and probably also light flash patterns, like fireflies. And they separate themselves out that way so that males can find females,” distinguishing “the tiny little differences between the structure of the bait.”
Once the male closes in, he bites onto the female, usually her belly, and their tissues fuse together to permanently join the pair in incredibly unholy matrimony. The male’s eyes and fins atrophy away, and here he will live out the rest of his life nourished by her blood, still breathing with his own gills and, importantly, still producing sperm.
“This establishes a hormonal connection,” said Pietsch, “so that probably the maturation of eggs and sperm is synchronized by the sharing of hormones. And once the eggs are mature and the male is ready, she extrudes the eggs” in a kind of gelatinous sheath that can be 30 feet long. This acts like a sponge, readily absorbing the water that the male has released his sperm into.