When flaccid, turtle penises look like a barrel-shaped hard structure tucked away inside their cloaca. But when sexually stimulated, these organs double upon themselves and bulge out.
Much like mammal penises, these inflated hydraulic cylinders can grow to half the length of the male body. And they certainly look horrifying.
The turtle penis is a long, deep-folded organ with a pair of glans at its tip. Unlike mammals, whose genitals are covered with a sheath at all times, turtles show their glans in full view. The glans are linear with seminal grooves running down them, and they open and close when the turtle is stimulated. The tip of the glans is a purplish head that throbs and pulses when the turtle is at work.
During resting periods, the turtle penis is flat and buried in the cloaca. But when it’s time to copulate, male turtles bulge their glans out of the cloaca. They do this a few times and then retract it back into the cloaca.
When the glans are inflated, they have a very similar appearance to the mammalian penis. That’s because the walls of a turtle penis are reinforced with layers of stiffening collagen fibres. The pattern of these fibres is arranged either along or perpendicular to the phallus’ long axis, and this arrangement caused Diane Kelly to title her 2004 paper “Turtle and mammal penis designs: anatomically convergent.”
The Seminal Grooves
Turtles’ genital organs look scary, but they actually function just like those of mammals. When a male turtle’s glans is ready for mating, it will fill up like a blood-inflated hydraulic cylinder. The glans also expand when the male mounts over the female.
The shape of the glans varies from one species to another. For example, in mud turtles (Kinosternidae), big-headed turtles, batagurid and emydid river turtles, the glans have a pointy medial process and a single sinus. But in leatherback sea turtles, the glans have distolateral lobes separated by a midline. And in New Guinea pig-nosed turtles, the glans has a tri-lobed appearance.
In addition to the glans, the penis contains a pair of long retractor muscles. When at rest, the phallus doubles up within the cloaca and is pushed outward by these muscles when it’s time to mount. The muscles are incredibly robust, as Scientific American reports; they’re described as “physiologically rugged.”
A turtle’s penis can be more than half the length of its body and is typically black or purple in color. While it may look weird, it’s critical to the reproduction of these reptiles. Just like the penises of mammals, a turtle’s glans can become traumatized, desiccated or dried out, and if it prolapses, it must be addressed immediately by an experienced reptile veterinarian.
While turtle penises might seem weird to us, they serve a very important purpose. They help to make sex more successful, which is an extremely important part of the mating process in these animals. This is especially true for some species, which live in environments with high predation pressure. They often need to be able to get their genitalia into their female partners’ cloaca in order to fertilize eggs.
As Scientific American reports, turtle penises have a single erectile body that becomes engorged with blood and expands like a hydraulic cylinder. This enables them to penetrate the female’s cloaca with greater ease than a regular mammal’s penis. The wall of the phallus is composed of collagen fibers and can become quite rigid, making it highly resistant to bending.
During the mating process, a male turtle mounts a female in order to push his penis inside her tail’s cloaca. He does this by hooking his tail under hers with a claw-like tip and bringing the cloaca together. He then inserts his phallus and shoots semen into the female’s cloaca.
Afterward, he may begin chasing the female around and bobbing his head up and down in front of her to let her know that he is ready to mate. If she doesn’t respond in a positive manner, the male might bite her neck to subdue her and force her to mate.
When erect, turtle penises can extend as far as half their body length, according to Darren Naish at Scientific American. The endpoint culminates in a five-lobed head that discharges semen from four different branches (think Ridley Scott’s Aliens franchise).
They don’t stay erect for long, however. When at rest, the genitals are flaccid and tucked inside the cloaca—the hole that turtles use to pee, poop, have sex, and sometimes breathe. It’s only when males are mating that they elongate the organ and expose its lurid, horrifying glory.
A glans-shaped turtle penis looks almost like a mushroom, with its long, linear shaft and wide seminal grooves. The glans are largest at the tip, which is purple in color. The glans are the only parts of the genitals that have skin, but they’re actually made of a thick layer of mucus that helps regulate temperature and protects against infections.
The glans also have a pair of retractor muscles that pull on the phallus to elongate and eject it from the cloaca. The elongated turtle dick is then used to penetrate a female’s cloaca and, after some swatting and head bobbing, seduce her into copulation. For the full experience, check out this video of a sexy turtle penis in action. It’s enough to give you a case of major penis envy.