World Oceans Day 2019 Part 3: Luring and Losing Lovers

This is Part 3 of a series celebrating World Ocean Day 2019 and the theme Gender and Oceans. Check out Part 1 and Part 2 to learn more about the wild and wonderful ways females play a role in long-term sexual success in the sea.

When it comes to sex, there’s an inherent tradeoff females must negotiate between attracting preferred mates and warding off those she has no interest in.  It’s not an easy task, and often, the effort to dissuade an amorous male can be costly…or even fatal.  In the following species, females demonstrate some creative ways to both attract mates they want and avoid those they don’t.

Love Potions

There’s a new singles craze happening around hipster neighborhoods these days.  Known as XXX, the events provide an opportunity for individuals to find their match by smelling one another’s t-shirts. While it may seem strange, the power of scent in seduction is one of nature’s oldest tricks of the trade. And it’s especially powerful in the sea, where chemical compounds travel easily through the water and can act as powerful intoxicants.

Illustration by Missy Chimovitz

Illustration by Missy Chimovitz

Female Maine lobsters use this to their advantage when faced with seducing overly aggressive large males during mating season.  Ready to attack any lobster that approaches their den, these large males are formidable and could easily crush a female. Lucky for her, she’s got a tried and tested love potion conveniently housed in her bladder. Yes, we’re talking urine. And in this species, a few spritzes of pee in the face is all it takes to convert the most agro male into a gentle lover.

When a female decides which male she wants to mate with, she approaches his den and then quickly shoots a stream of urine into the opening as the male lunges out.  In lobster, the bladder sits above the brain and links—conveniently—to two nozzles just below the eye stalks.  So, she can squirt pee forward and then scram before he attacks.  She then repeats this for a few days.  After about a week, the effect takes hold, and the male begins to warm to her unique scent.  Eventually, he invites her—and only her—into his den to hang out and eventually mate, once the female molts.

It’s a kinky affair, but for female lobster, golden showers are a must when it comes to safe sex.  

Faking It

Cephalopods—octopus, squid, and cuttlefish—are known for their remarkable color-changing abilities.  Often, we think of these talents going toward camoflauge—to help with attacking prey, or avoiding predation.  But these abilities can also help with sex.   Often, it is the males who use their patterns to attract females—or fool rival males—as we see, for example, in cross-dressing male cuttlefish. But females make use of their dynamic skin, too.

In fact, in one squid species, females are known to adjust their coloration to mimic males—specifically, the dark shading where the testes lie—as a way to deter unwanted mates.  These females tactfully fake having male parts on the inside, by changing their skin tone on the outside. And the ruse works.  Studies show that females with this specific coloration are harassed less by courting males.

Maze-Like Vaginas

For most mammals, the female vagina is a straight tunnel. And a clear pathway to get sperm to the egg.  Not so in some small whales and dolphins.  Instead, we find a complex obstacle course of twists and turns, flaps and folds, blind alleys and dead ends.   It’s a gauntlet. And we are still trying to understand what it’s for.  Afterall, building these structures takes energy; evolution doesn’t just make this kind of stuff for fun.


One theory is that we tend to see these structures in species where females likely have little control over mating, and may be subject to multiple copulations by multiple males in quick succession.  With little ability to screen mates prior to mating, Dr. Sarah Mesnick and Dr. Dara Orbach,  hypothesize that perhaps these complex structures could work to help “screen” mates simply by making it hard for sperm to get to the egg—only the most tenacious, or “fit”, sperm will succeed.  It’s also possible that the female could somehow close or open, via muscular contractions, different pathways, making it more or less easy for sperm to reach the cervix.  For now, what we do know is that understanding whale vaginas may tell us a whole lot more than just how big a whale penis is. To learn more about how one actually studies a whale vagina, check one of my all-time favorite blogs: Getting To Know Whale Vaginas in Seven Steps.

 And that’s the end of this series honoring some of the more unusual and impressive female strategies that help govern successful sex in the sea.  Be sure to check out Part 1 and Part 2 if you missed them. Hope you found it intriguing and inspiring.  And here’s to a future where Gender and Oceans no longer needs to be a theme for World Ocean Day; rather, inclusivity and understanding are the norm and in so doing, we’ve accelerated sustainable solutions for our oceans across the world.

World Oceans Day 2019 Part 2: Female Parrotfish Do Math for Better Reproductive Odds

Illustration by Missy Chimovitz

Illustration by Missy Chimovitz

This is part 2 of a three-part series honoring World Ocean Day 2019’s Theme of Gender and Oceans. See Part 1 here

Like many fish species, parrotfish form harems.  Because sperm is cheap to make, one male can produce plenty of it—enough to fertilize all the eggs of many females.  And like many harem-forming fish species, parrotfish sex changers, starting life as a female and then transitioning to male.  This strategy allows an individual to reproduce when small (as a female), and then when big enough to fight for and win a harem of females, they can transition to male and boost their reproductive output.

That’s usually what happens. But in bucktooth parrotfish, the largest female doesn’t always change to male when given the opportunity. Why?  Because sometimes, the transition just doesn’t add up when it comes to potential offspring output.

Bucktooth parrotfish, S. radians.

Bucktooth parrotfish, S. radians.

For fish, the bigger you are the more eggs you make. A very large female may produce ten times more eggs than a female half her size (we mammals are very different in this sense—all females have roughly the same number of eggs to start with, and that number goes down as we age). And somehow, female bucktooth parrotfish get this math…and act on it.

 If the largest female is so big that she produces more eggs than all the other females combined, she won’t transition to male.  A smaller female then takes up the male role, willing and able to fertilize all the eggs of the biggest female, plus the other females in the bunch.  

 Just how the big female conducts this calculation remains a mystery. But for this species, a little math goes a long way towards successful sex in the sea.For more details on this amazing strategy, see here.

Stay tuned for Part 3 of Sex in the Sea’s World Ocean Day: Gender and Oceans series.

World Oceans Day (WOD) 2019: Gender and Oceans Part 1

This June 8th, the UN’s theme for World Ocean’s Day is Gender and Oceans—a fitting subject as research highlights the importance of women in the long-term health of fisheries, the oceans, and communities worldwide. To honor this important theme, I’ve got a three-part series highlighting just some of the more fascinating female-driven strategies for successful sex from beneath the waves.  Here’s to celebrating the critical and awesome role of females in securing a sustainable future for the oceans—above and below the surface. Happy World Ocean Day!

WOD Part 1: Personal Sperm Banks Are Oh So Convenient

Finding a mate across the seven seas can be a right pain in the ass. It’s a lot of water to cover, and in three dimensions, don’t forget.  Instead of having to constantly search for and secure a mate, many females have instead  found ways to gather sperm and keep it—for when the timing’s right for reproduction.  Whether it is simply storing sperm in her uterus, or harboring the whole male inside her, these females have mastered the art of sperm-on-demand.

Ordering Sperm-to-Go

In sharks, females are known for their ability to store sperm for over three years after their last known mating and then use that sperm to successfully reproduce.  First observed in aquaria, this phenomena is seen across multiple species likely far more common than we had realized.  

In some squid, males place sperm packets onto females, often around her head.  Somehow, these sperm make their way through her body to a sperm storage receptacle.  When she’s ready, she releases her eggs, which pass by this holding tank and become fertilized in the process. 

The brownbanded bamboo catshark can  store sperm for over 3.5 years . Photo credit: Timothy Wong.

The brownbanded bamboo catshark can store sperm for over 3.5 years. Photo credit: Timothy Wong.


Keeping Him Close…Very Close

In the deep sea, we see a different twist on the personal sperm bank strategy.  There, Ceratioidei anglerfish females attract tiny dwarf males to them via chemical signals and then fuse their bodies with these parasitic mates.  The permanently attached male receives nutrients from the female and in return, provides her with sperm on demand.  In fact, that is his sole role in the relationship, given that most of his other internal organs dissolve in the fusing process.  Check out this awesome comic by the fantastic Oatmeal for a great summary of this strategy and see this amazing footage of a live female and male pair, caught on video for the first time.

An inside job

Spawning female Osedax worm. Photo credit: G. Rouse.

Spawning female Osedax worm. Photo credit: G. Rouse.

Female osedax worms take the personal sperm banks even farther—storing not just sperm but the entire male inside her body.In fact, it is likely that the female “makes” her own males by releasing a chemical that stunts the growth of nearby larvae swimming by and triggers them to develop testes. Microscopic and stuck in this pre-pubescent state, the tiny males swim down the female’s tube and gather around her ovaries. There, they spend their days pumping sperm out of holes in the tops of their head.A single female may have hundreds of these males working away in side her. Perhaps “sperm factory” is a better term than sperm bank, but, well, you get the idea. For more on this wild strategy, check out this episode on Stuff To Blow your Mind Podcast.

Check out Part 2 and Part 3 of the series, celebrating female-driven strategies for sexual success in the sea as part of World Ocean Day 2019: Gender and Oceans!