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Dangerous Dating: 4 Animals That Take Love to the Extreme

A photo of a praying mantis eating her mate
A praying mantis eating the male after mating. Photograph by Sivitri Delphia, National Geographic Your Shot

Finding true love is difficult no matter what species you were born into—but at least humans don’t have to worry about being eaten on a first date.

Black widow spider and scorpion females famously kill and sometimes eat males after sex. Of course, not all animal courtship is risky or dominated by females, “but in the science community, we’re often intrigued by the dangerous ones,” said Maydianne Andrade, an animal-mating expert at the University of Toronto, Scarborough.

See below for our Valentine’s Day roundup of wild animal mating rituals. (Related: “Wild Romance: Weird Animal Courtship and Mating Rituals.”)

Black Widow Spider

Of the many black widow species found around the world, the Australian redback (Latrodectus hasselti) has an exceptionally complex dating history. (Watch a video of the deadly black widow spider.)

In Australia, 80 percent of male black widows never find a mate, so it’s common for a handful of males to sit on a female’s web and compete for her attention.

Since the females have the upper hand, they put males through an endurance test: The male that can wait on the web the longest—typically the largest or the one with the most energy—usually wins and gets the chance to pass on his genes. (Related: “Male Black Widow Spiders ‘Twerk’ to Avoid Being Eaten by Females.”)

Male courtship is more common when females have enough males around to be choosy, Andrade noted.

Also, for these males, one chance encounter may be the only opportunity they have to find a mate.

“Females will get to mate without even trying,” she said. “What gives males the edge is whether or not they have good genetics,” which are on display during courtship rituals.

Flatworms

Unlike black widow spiders, flatworms don’t fight with competitors—the hermaphrodites fight with each other to determine which one will be the male in the relationship.

Their first “date” is an hour-long penis fight during which the flatworms try to stab each other through the skin. (Related: “Why Sea Slugs Dispose of Their Penises.”)

The first flatworm to stab the other one is the father, and he gets to float away without any further responsibilities. The losing flatworm has been impregnated by the jab and needs to invest more energy into finding food and safety.

Black Devil Anglerfish

The black devil anglerfish (Melanocetus johnsonii) is a clingy boyfriend. These fish can be found at depths of around 6,600 feet (2,000 meters), where there are slim pickings.

The male fish is much smaller than the female. He also has a digestive system that shuts down once he reaches adulthood, so he desperately searches the ocean for a female anglerfish. (Also see “Photos: Rare Deep-Sea Anglerfish Recorded.”)

As soon as he finds her, he bites into her belly—dissolving the skin—and continues to live off of her for the rest of his life.

Praying Mantis

Another femme fatale, the praying mantis is a notorious sexual cannibal, often attempting to eat the male before mating is over.

To find a female, the male mantis continuously sniffs the air. Once he catches a whiff of a nearby female, he approaches her and displays a little dance. If she likes the way he moves, she will allow him to mount her before trying to bite off his head. (Also see “Praying Mantis Mimics Flower to Trick Prey.”)

There are plenty of other interesting courtship displays around the world, including the strut of the greater sage-grouse, salmon that fight upstream to spawn, and turtles that desperately cling to each other to mate. (For more videos, check out National Geographic’s “World’s Weirdest” collection on YouTube.)

What are some other interesting dating techniques that you’ve seen? Let us know in the comments. 

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