Detachable penises. Genital plugs. Sexual cannibalism.
Dating and mating in the animal kingdom aren't just complicated — they can be fraught with violence and danger. Even so, they're the only game in town. Every species must reproduce, and there are many paths to successful reproduction, though those paths may sometimes be as convoluted as the corkscrew genitals of a mallard duck.
The prospect of exploring mating positions in frogs, porcupines' use of sex toys or hermaphroditic sea slugs' penis spines might seem daunting to some, but not so for biologist and writer Carin Bondar. She leads the way into the intriguing world of animal sexual practices in her new book, "Wild Sex: The Science Behind Mating in the Animal Kingdom" (Pegasus Books, 2016). [Top 10 Swingers of the Animal Kingdom]
From finding a mate, to procreating, to dealing with the successful outcome of mating — offspring — "Wild Sex" investigates the often-harsh realities of sexual behaviors practiced by animals large and small.
Bondar is the current lead presenter for Discovery World's "Brave New World with Stephen Hawking" and host of the web series "Wild Sex" for Earth Touch News Network. She has appeared on Discovery Channel's "Outrageous Acts of Science" and has hosted online and television programs created by National Geographic Wild, Scientific American and the Science Channel.
Recently, Bondar spoke with Live Science about the unusual sexual behaviors and equipment used by humans' closest relatives and most distant cousins on the tree of life, and what people's interest in animal sex reveals about them. [Live Science Book Giveaway: 'Wild Sex' by Carin Bondar]
(This Q&A has been edited for length and clarity.)
Live Science: What was it about sex in the animal kingdom that first attracted your attention as a biologist?
Bondar: Ironically, it happened when I was at home enjoying the young products of my own sexual activity — my children. I started blogging, and though I didn't just focus on sexual topics, I noticed engagement was so much higher when the topic was sex — and the crazier, the better! So I rolled with it and went more in that direction. And then I got a call from Earth Touch [News Network] to write and host a series about animal sex, and six weeks later, I was on a plane to South Africa. It just swept me up in its own tidal wave.
LS: For many people, sex is primarily about pleasure. How much is pleasure a factor for animals?
Bondar: Very, very little! Unfortunately, there's a massive dichotomy between sexual cells of males and females, so males have incredibly abundant sperm, and females have very rare and expensive eggs. Generally speaking, males always want to have more sex and get as many partners as they can, and females want to be protective of their expensive treasures and choose carefully who gets to fertilize them.
From bugs to mammals and everything in between, this sets the scene for violence, conflict and war. There's no champagne, no roses. It's very much, "I've evolved these structures to torture you and hold you down so I can have sex with you."
LS: What are some of the risks that animals in certain species face during sex?
Bondar: Bedbugs and some of the nudibranch species use what is aptly termed traumatic insemination, because it literally is a stab wound to the female's body. The sperm will travel from these wounds into her ovaries, so she basically ends up with stab wounds all over her body that can get infected, which could certainly affect her well-being and general health. [Animal Sex: 7 Tales of Naughty Acts in the Wild]
Some canine species have penis bones that get massively inflated during sex, so they can't separate. That's actually an evolutionarily smart thing to do, to not let your female get away until you get sperm in there, and it's also a fail-safe for the male, who can't get out until he finishes the job. But it comes with a huge element of danger from predators.
Then, there are a lot of invertebrates that are hermaphroditic, male and female at the same time. Sometimes they can fertilize themselves, but often they need an actual partner. Taking the male role is more favorable because it's less work, so these sexual encounters tend to become extremely violent.
LS: What about spider and insect species where males are cannibalized by females during sex? That seems like even when a male succeeds at reproducing, he loses.
It seems horrific to us, but it's reproductively clever — these males can actually increase their reproductive success by dying!If the female is busy feasting on his body, she's not out getting more sperm, so his sperm can dominate.
In mammals where sperm is so plentiful, it's a vastly different story than in spider species, where males only have one or possibly two chances to copulate in their entire lives. [101 Animal Shots You'll Go Wild Over]
We see the same thing in those infamous preying mantis videos where the female rips the male's head off — his genitals are still doing the deed while she's busy eating his head and body. His sperm has lots of time to travel where it needs to go, and she's not seeking new sperm. That's kind of a tough one for us to swallow (so to speak), but it is a reproductively sound strategy.
LS: Many species appear to engage in a type of "arms race" when it comes to sex, with female behavior or biology thwarting male advances, and male strategies and anatomy trying to work around that. But don't they want the same thing — to procreate?
Bondar: They do. However, they want it on their own terms.
These arms races are ridiculous. Like in the water strider, males have evolved these crazy structures that fit around eyeballs of the females to keep them in place, and the females have these anti-grasping spring things that they can use to spring males off when they're trying to have sex with them.
We assume as biologists that animals ultimately want to maximize biological fitness, in terms of getting their genetics to the next generation. But the problem is that females don't want just any sperm. They want the best sperm. Males, on the other hand, because it's so easy for them, they can afford a few missteps.
If I'm a male, and I put my sperm out there as often as I possibly can and with whomever, some will be bad mothers or bad children. But I'll do better in the long run. For females, it's a completely different story.
Think of the human case. If I get fertilized, I'm out of reproductive commission for at least another nine months or more, as I then breast-feed, so that takes me out of the reproductive game for close to a year. If I let any man fertilize me willy-nilly (pun very much intended), I'm jeopardizing my own biological fitness, because that's a huge commitment for me. I'm doing this huge thing in my body for the embryo.
LS: I was going to ask for the most extreme example of a sexual behavior, but … there are so many. Is there one in particular that stood out to you when you were researching this book?
Bondar: There's one of those hermaphrodites I was talking about, a sea slug. As many hermaphrodites do, each one is trying to be the male. What this species in particular does is it takes its razor-sharp penis and stabs the partner directly in the forehead. And they're doing this with a degree of accuracy and precision that's unprecedented.
Biologists puzzled about this for long time, until scientists looked at the chemical makeup of what was getting deposited. And they found that there was some kind of neurochemical warfare going on. They were ejaculating into the cerebral ganglia of the receiving partner, so they manipulated the partner to become more female. Since being female is more expensive, it makes sense for them to want to be the male as much as possible.
The other one that I really like is a cannibalistic spider species. Like many other species, they have something called a mating plug, something that plugs up the female's genitals after she's been fertilized. Sometimes males put them in, and sometimes females seal themselves up.
In this species, females take the substance they'd use to seal themselves up, and they use it to ensnare males because they're hungry. They make their genitals into a spider-sized sticky trap. A male comes along, and she'll trap him. He'll die there, and she won't necessarily eat him right way. So she'll be walking around with a dead guy on her genitals until such time as she decides to eat him.
LS: What might all these examples of different animal sex practices mean for readers in terms of understanding their own sexual behavior?
Bondar: The breakdown of the book — trying to find a mate, trying to have sex with your mate and then dealing with the aftermath of the sex — that affects us just like it does every other animal.
It's funny and gruesome and horrible to talk about all these "insert part A into slot B" examples, and people like to hear about that. But the reason people are so interested in sex in other animals is [because] we're so obsessed with it in our own lives. I always like to bring it back to humans remembering that we're part of the animal kingdom, even though we often pretend that we're not.
"Wild Sex: The Science Behind Mating in the Animal Kingdom" was published Aug. 6.
Original article on Live Science.