Image Courtesy of Donald McKnight

Turtles have been around since the time of the dinosaurs, but they now are struggling to survive, with about half of all species threatened with extinction. To save them, scientists need accurate data on how many males and females of each species are left, but there’s a problem—the two sexes can look essentially identical, with the male’s penis tucked inside his body when he is not aroused. So, what is a scientist trying to properly conduct research to support conservation to do? Whip out a vibrator, of course.




Donald McKnight, a Ph.D. Candidate at James Cook University in Australia, was studying western chicken turtles for his master’s degree. “To really understand what is going on with a population and how to conserve it, you need to be able to distinguish males and females,” McKnight told Gizmodo. But he wasn’t confident in the published criteria for distinguishing sexes, and other ways of sexing when visible characters aren’t definitive are very invasive. One option is to literally cut open the turtle to examine its gonads, said McKnight, a procedure which may weaken the animal, make it vulnerable to infection, or even be fatal. “We weren’t doing this because we thought it would be fun,” McKnight emphasized. “We did this because we were trying to find a less invasive method of sexing problematic turtles.”

That’s when McKnight and his colleagues, Hunter Howell, Ethan Hollender, and Day Ligon, stumbled upon a 2013 paper which described the use of vibrators for collecting sperm from turtles. “It seemed reasonable to us that if you could use a vibrator to make a turtle ejaculate, then you should also be able to use it to make a male turtle show you his penis, which would then allow us to distinguish males and females.”


“We weren’t doing this because we thought it would be fun. We did this because we were trying to find a less invasive method of sexing problematic turtles.”

So, the team went online and bought the cheapest vibrator they could find—a small, silver bullet-style sex toy—and went about collecting turtles from four species to test the method. “We held the turtle at an angle so that the bottom portion of its shell was facing the researcher,” McKnight explained. Then they “would slowly move the vibrator around to different parts of the turtle and watch how it responded.”

Perhaps unsurprisingly, the silver bullet wasn’t, uh, a silver bullet. Much like with people, the effectiveness of stimulation depended on the individual. Some species were ‘easier’ than others—softshell turtles, for example, readily responded to attempts at stimulation, while common musk turtles did not. And within a species, individual preferences varied. “If we did something that the turtle didn’t like, it would tense up and tuck its limbs and tail against its body, but when we found a position or motion that aroused it, it would relax and stretch out its limbs and tail, so we would keep doing that,” McKnight said.

They found that direct stimulation of the tail—where the penis is sheathed—was usually the trigger for erection, but again, much like us, the animals needed a bit of warming up first. “We had to vibrate elsewhere and periodically test the tail to see if they would let us keep the vibrator there without tensing up.” The researchers published their findings in a recent paper in Acta Herpetologica.


“Also, it appeared that the turtles responded best when the vibrator had fresh batteries and was on its fastest setting.”

Image Courtesy of Donald McKnight


The variability between the individuals and species fits with what previous researchers have found when trying to bring turtles to climax for sperm collection, said Brian Todd, an associate professor in the Department of Wildlife, Fish and Conservation Biology at University of California, Davis. “In Sherri-Anne Carter’s work, she had a figure caption that literally read “Silver bullet-design vibrator” and “the design was chosen depending on the size of the individual turtle.” Apparently, larger turtles need larger vibrators!”



Back in 2010, when he was working on western pond turtles, Todd witnessed firsthand how effective at stimulating vibration can be. “We mark turtles by using a metal file and notching the edge of their shell, and for many male turtles, the vibrations on their shell seems to stir something in them. Imagine my surprise the first time a large male ejaculated all over one of my graduate students!”


Todd told Gizmodo that although the vibration method for ejaculation has been known for some time, it isn’t commonly used in the field for sexing turtles. He’s not convinced it will be useful for many researchers, as there are visual characteristics that can distinguish males, such as longer tails and curved plastrons (the bottom part of their shells). “Not all turtle species have sexes that are told apart so easily, however, so the method of using a vibrator can be useful in some circumstances,” he said. And if the study does want to collect semen, he added, then vibration is by far the least invasive method.

“Imagine my surprise the first time a large male ejaculated all over one of my graduate students!”


James Van Dyke, a lecturer in Ecology at Charles Sturt University in Australia, said he’s considering trying the method on some Australian turtle species , although he’s uncertain which model to use (“I imagine that size would matter, as a very large vibrator may not be able to reach into the shell to stimulate the best part of the tail, whereas a smaller vibrator could reach into the little nooks and crannies.”) Despite McKnight’s observations, Van Dyke worries that powerful vibration will cause the turtles to clamp up rather than let loose. “My gut feeling is that it will simply cause them to pull tighter into their shell.”

McKnight hopes for further studies will shed light on how well vibration works in other species, as well as the effectiveness of different vibrator models with varying sizes, shapes, pulse patterns, and textures—although for now, he’s leaving that work to other curious minds. He emphasized that despite how they might sound, these studies are not silly or for the researcher’s amusement. “I think that it is really important to stress that this method is less invasive and less traumatic for the turtles than the alternative methods, and that’s why we tried it,” he said.


“I know this method sounds weird, but if it works as well as advertised, it needs to be in the toolkit of turtle biologists and conservationists,” Van Dyke told Gizmodo. “Being able to tell males and females apart is one of the first major hurdles in assessing and mitigating [threats] to a species.”

Christie Wilcox is a science writer, author of Venomous: How Earth’s Deadliest Creatures Mastered Biochemistry, and all around biology nerd. Follow her on Twitter.