By Madeline McCurry-Schmidt
A reader recently asked me to look into one of nature’s big mysteries: how do turtles have sex?
With their clunky shells, turtles (and tortoises) seem about as penetrable as armored cars. But they’ve got to reproduce.
How the heck do they do it?
1. Loudly. Here’s a video of two giant tortoises getting busy:
Hopefully, you didn’t start that clip at work. The male’s loud grunting is super awkward. But you’ll notice that these turtles, despite their shells, aren’t doing anything unique. The male is mounting the female from behind–just like the way pigs or frogs or ladybugs do it. The tortoises are doing it doggy-style.
But that’s where many similarity between turtles/tortoises and other animals end. Because turtles and tortoises also do it…
2. Creatively. Turtles and tortoises, which fall into the order Testudines, don’t have what we would think of as vaginas or penises.
Like most birds, female turtles have “vents” called cloaca. The cloaca is the opening for feces and urine. Some diving turtles even use their cloaca for respiration underwater–they have extra air bladders connected to the cloaca, which help them absorb oxygen from water.
Cloaca are also the openings for sexual reproduction. With most of their bodies covered in shells, turtles have to make the most of the holes they’ve got.
Male turtles also have cloaca, and from their cloaca emerge some strange-looking penises. Some have compared turtle penises to “opening flowers” and others have called them “terrifying.” Turtle penises can be as long as 30 centimeters and are usually a dark, eggplant-y purple.
Despite their odd appearances, turtles clearly have the right parts for sex. And, thanks to evolution, they’ve also got the anatomy to reproduce…
3. Efficiently. It’s one thing to reproduce doggy-style, but doggies don’t have shells. Luckily, male and female turtles have evolved differing shell-shapes that help them get closer during intercourse.
Female turtles are on the bottom during sex. Her rounded upper shell, called a carapace, makes it tricky for the male to lower his penis close to her cloaca. So males have a slightly concave lower shell, called a plastron.
Of course, sexual reproduction varies between species of turtles and tortoises. But it always ends with the same scene: laying eggs.