Rough sex & other recent discoveries in sawfish reproduction

*Blog co-authored by Marah J Hardt and Danielle Baldwin

Researchers secure a 14ft pregnant female sawfish for tagging. Photo credit:  FSU Coastal and Marine Lab.

Researchers secure a 14ft pregnant female sawfish for tagging. Photo credit: FSU Coastal and Marine Lab.

Some people like it rough – whips and chains, but what about…chainsaws? For the endangered smalltooth sawfish, sex may not be that S & M, but having a three-foot long snout studded with teeth attached to their face does means "business time" can get a bit messy. And one can only wonder about reproduction itself—just imagine giving birth to a young with a serrated knife attached to its head—Happy Mother’s Day, indeed.

So how do they do it? We had few clues—until now. Despite their enormous size and shallow, nearshore habitat, sawfish, like so many other sharks and rays, have historically kept both their mating and birthing rituals hidden from scientists. But over the last six months, an explosion of scientific research on sawfish sex has advanced our knowledge of the species and contributed critical information to support their recovery.

Researchers at FSU secure a sawfish for tagging. Photo Credit:  FSU Coastal and Marine Lab.

Researchers at FSU secure a sawfish for tagging. Photo Credit: FSU Coastal and Marine Lab.

The most recent findings build off work from about two years ago which first lifted the veil on sawfish reproduction. That’s when a team of researchers used DNA to prove female sawfish are capable of virgin birth—the first case of such parthenogenesis of any shark or ray in the wild. As discussed in Chapter 5: Inner Chambers in SEX IN THE SEA, the discovery hinted that when mates were hard to find—perhaps due to their low numbers because of overfishing—the females could continue to reproduce on their own. Parthenogenesis is a survival technique that could help with short-term recovery but, because of reduced genetic diversity, it’s not great for long-term success of the population.

This study gave us a peak behind the curtain of sawfish sex. For seventeen years, scientists had used surveys, satellite tracking, and tagging to identify pupping and nursery grounds, but we had still never witnessed live birth or confirmed where sawfish mated (even though females can reproduce sans males, they also do have sex).

That all changed in December of 2016, when Dr. Dean Grubbs, Associate Director of the Florida State University Coastal and Marine Laboratory, and his team witnessed a female giving live birth to several pups.

Dr. Dean Grubbs and team assist pregnant female smalltooth sawfish with live birth. Photo Credit:  FSU Coastal and Marine Lab.

Dr. Dean Grubbs and team assist pregnant female smalltooth sawfish with live birth. Photo Credit: FSU Coastal and Marine Lab.

This rare encounter revealed just how these badass mamas endure the process: a thick sheath of tissue wrapped around the pup’s razor sharp rostrum when it is born protects the mother.

Protective sheath covers the razor-sharp teeth along the newborn pups rostrum, protecting its mother during birth. Photo credit:  FSU Coastal and Marine Lab .

Protective sheath covers the razor-sharp teeth along the newborn pups rostrum, protecting its mother during birth. Photo credit: FSU Coastal and Marine Lab.

The unique biology of the birthing process wasn’t the only exciting find— the event also confirmed that sawfish give birth in the Bahamas. Before this, Florida was the only known pupping ground. Further research will help determine if the populations in Florida and the Bahamas intermix, which would be a good thing for boosting genetic diversity of the remaining populations.

Check out a video of the pregnant female and her pups by the Field School, here:

Then, in April of this year, Dr. Grubbs was able to confirm that male and female sawfish used the Everglades National Park as a lovers’ lane. "We’ve long assumed sawfish mating was a rough and tumble business, but we had never before seen fresh injuries consistent with recent mating, or any evidence that it was happening in areas we’ve been studying primarily as sawfish pupping grounds," said Dr. Dean Grubbs. "Figuring out where and when sawfish mate, and whether they do so in pairs or aggregations, is central to understanding their life history and ecology."

Bite marks and other scars are typical signs of the rough sex common in sharks and rays. By discovering fresh wounds on adult sawfish, the research team now suspects that the Everglades are not only where mama sawfish give birth, but also where the next generation is conceived.

Fresh cuts on the underside of a sawfish captured in Everglades National Park hint at probable active mating. Photo credit:  Tonya Wiley .

Fresh cuts on the underside of a sawfish captured in Everglades National Park hint at probable active mating. Photo credit: Tonya Wiley.

This new information is vital for effective management of sawfish. In 2003, the smalltooth sawfish became the first native marine fish species listed as Endangered under the U.S. Endangered Species Act. Since that time, the additional four species of sawfish have all been added to either the Endangered or Critically Endangered lists as their natural populations dipped to less than 10% of their historic levels due to loss of natural habitat or overfishing. Sawfish are prized by some cultures not only for the uniqueness of their rostra, but for their fins and liver oil.

As of 2007, the import for sale of any sawfish species became illegal in the U.S. So while legislation is helping to save this species, understanding more about their mating habits is necessary to ensure effective conservation efforts.  Now that the Everglades have been identified as both a pupping and mating ground of these endangered species, the continued protection of this critical habitat is even more important than ever.

The Everglades National Park. Photo credit:

The Everglades National Park. Photo credit:

These recent discoveries demonstrate that the science of sex in the sea continues to unfold at a rapid pace—and continued support of this basic research is paramount to effective management. This work also points to the importance of funding—not just for continued research, but also for continued protection and maintenance of the national parks that protect these animals. Protections that are currently under threat.

"Florida’s sawfish have a long road to recovery, but exciting breakthroughs so far provide lessons and hope for other endangered populations around the world," said Sonja Fordham, President of Shark Advocates International, a project of The Ocean Foundation. "The new findings can help efforts to protect sawfish at critical times, but also highlight the need to protect the park system that ensures suitable habitat, the funding for research, and the overarching law that has made success to date possible."

This link provides ideas for how to support national parks-- financially and beyond, including calling your representatives in the House and Senate and letting them know these special places matter to you (and while you are on the line, let them know you also support science-based decision making!). And if you are a scientist, consider adding your name to this recent letter, requesting continued support for our national marine protected areas.

The SexSea-ist Discoveries for 2016

As usual, sex in the sea in 2016 was in full swing, as was the science behind it, with new discoveries cropping up from the shallows to the deep.  Here's a look back over some of the sexiest and saltiest science of the year:

1. Nature's smallest go for big foreplay

One of the tiniest and toughest among us, tardigrades showed us their penchant for the extreme now extends to marathon mating sessions. Scientists released the first ever sex tape of these micro maters, and it showed a whopping  Over an hour of foreplay leads to ejaculation which leads to fertilization of the eggs—which are laid in the outer most layer of the female’s skin. And, should fertilization fail to occur, the female can reabsorb her eggs, saving precious resources. Just another superpower to add to their impressive list, which includes survival in nearly any environment, on earth or outer space. 

2. Ladies First Leaves Fiddler Females Coerced

Australia National University, via  Science Daily

Australia National University, via Science Daily

In fiddler crabs, competition for mates is fierce. To lure in the ladies, males wave their one enormous claw, which in banana fiddlers, is an alluring bright yellow. Then, an interested and scrutinizing female typically follows a male into his burrow, inspecting the digs before deciding to lay a clutch of eggs or not. But this year, scientists discovered that some males take a more devious approach to seduction. Stepping aside, the male encourages the female to enter first and then slips in behind her, blocking her escape. Trapped in the burrow, nearly all these females lay at least some eggs…in exchange for their freedom.

3. Chalk Bass Are Champion Sex-Swappers

Hermaphroditism and monogamy are both relatively rare in nature. But the chalk bass, a small Caribbean reef fish, dishes out both.  Researchers studying this species found that although they live in large groups, partners tend to be loyal, forming strong mating pairs throughout the mating season. Not only do they stay faithful, but each fish takes turns acting as female and male—alternating roles up to 20 times a day.  Such equitable sex swapping ensures each partner spends the same amount of energy reproducing as the other. Fair play indeed.

4. Virgin Birth in Sharks is Getting Popular

Photo credit:  Reef Builders

Photo credit: Reef Builders

We’ve known for several years now that some female sharks like to go it alone. In a form of reproduction known as parthenogenesis, these females deliver offspring that are 100% made from their mother’s DNA. (This trick is just one of several funky sex strategies found in sharks and rays).  This summer, leopard sharks joined zebra sharks, hammerheads, blacktips, and several other species in the growing ranks of a no-longer-so-exclusive virgin birth club.

And, in a related find, scientists (including Sex in the Sea-featured Dr. Dean Grubbs) witnessed the live birth of the endangered sawfish—a known virgin-birther—in the wild for the first time, just this month!

Dr. Dean Grubbs and colleagues assist and document sawfish live birth. Photo credit:  FSU

Dr. Dean Grubbs and colleagues assist and document sawfish live birth. Photo credit: FSU


5. Sex Appeal of Amphipods On the Rise?

Photo credit: Adelaide university via

Photo credit: Adelaide university via

Climate change in the sea—both warmer temperatures and more acidic waters—has proven detrimental to sex in the sea for many species. Amphipods, however, may be one of the exceptions. A lab-based study this year showed that warmer and more acidic waters helped accelerate growth in male amphipods, especially their manly claws. And, the bigger the claws, the sexier the male. The result? More pregnant females and an ensuing population explosion. Good news for amphipods; unknown consequences for the rest of their ecosystem.

Barring any major New Year's Eve revelations, that's a wrap for 2016. It's been a helluva year for Sex in the Sea. Thanks for continuing to follow along. I'm excited to see what new seductive forces, deceptive dotings, and oddly shaped genitalia we discover next as the science of reproduction in the oceans continues to unfold...and with it, endless opportunities for fine-tuning our own relationship with marine life.  Sex and sustainability go hand in hand; here's to a 2017 full of great salty, sex-focused science and solutions. 

The Spectacular Synchronized Sex of the Great Barrier Reef

Americans aren't the only ones to indulge in an annual glutinous feast in November. On the other side of the globe, millions of marine species, from small worms to giant fish, satiate themselves on the torrents of fatty, juicy eggs and sperm set forth by the corals of the Great Barrier Reef. Following the full moon of November, millions of tiny coral polyps, no bigger than a pencil eraser, coordinate an impressive synchronized sex act that stretches across more than 1000 miles—fueling the next generation of corals and feeding the current generation of reef residents.

For those lucky enough to be diving on the reef this time of year, the experience is akin to swimming through a blizzard, only the snowflakes are bright pink and rise upwards, rather than falling down. Because most of the action happens at night, the floating bundles of eggs and sperm can also create the illusion of outer space, as if the salty depths suddenly swapped places with the starry heavens above.

The effect stems from hundreds of coral species all releasing their gametes within a few minutes of one another, timing their once-a-year climax perfectly with a few thousand of their nearest neighbors. Even more impressive, each species goes off at a different time than other species throughout the night, and over the course of several days. This separation of spawning in time helps to reduce the chance of inter-breeding. This allows the eggs from one species meet and mingle with the sperm from that same species and not another (listen to this Stuff to Blow Your Mind podcast for more details on how this all works). Such impeccable timing maximizes the fertilization success of each species, and minimizes the risk of forming hybrids—which in general are bad news (but not always).

(Pause here for a moment and just imagine trying to perfectly coordinate that final release with your own partner after an entire year of build-up...and then having to match the timing with everyone in your home town. Corals accomplish this remarkable feat every year—and they do it without the aid of a brain.) 

Coral releasing egg-sperm bundles. Photo credit:  Auscape UIG/Getty  via

Coral releasing egg-sperm bundles. Photo credit: Auscape UIG/Getty via

After release from the bottom-dwelling parent colonies, the bundles float to the surface where they break apart, allowing sperm from one colony to mix with eggs from a neighboring colony. This is how corals date and mate, without ever having to move.

Fertilization happens, and a few weeks later, the larval coral sinks down from the surface to settle atop existing reef. The young coral cements itself to its ancestors' old skeleton and  goes on to build the next layer of living reef. 

The grandeur of the event is only matched by its importance: this is the only chance corals have to reproduce each year. It's a small window of opportunity to establish the next generation of corals—an accomplishment that is harder than ever for corals to achieve.

Turns out that John Oliver can count on corals to join the rest of us in bidding a fond farewell (NSFW) to the crap year 2016 was. Starting in February, a mass bleaching event killed more corals than ever recorded in modern history. In the northern part of the reef especially, the death toll reached over 95% on some reefs, with a loss of over two-thirds on many reefs. 

Image Credit: Terry Huges via Twitter

Image Credit: Terry Huges via Twitter

Such devastation is a double whammy for corals: first, there are fewer adult colonies left to spawn; second, those colonies that are left are spaced farther apart, making it harder for eggs and sperm to meet and mingle. The jury is still out on how this mass bleaching event will affect reproduction overall but initial studies show that in the northern reef, spawning was indeed less than in previous years. Similar results were found in previous research looking at bleaching impacts on coral reproduction in the Caribbean.

Such effects make this year's mass spawning even more impressive—a natural phenomena that is truly phenomenal, and worthy of celebration. But we must do more than marvel at this spectacle; we must also re-double efforts to protect what is left. That means not only fighting climate change, but also reducing local impacts from land-based activities such as mining. 

In addition to helping to protect what is left, scientists are also working to assist coral ecosystems with adapting to anticipated climate change.  Such "designer reefs" are not yet reality, but the approach offers one potential pathway forward for future reefs.

Scientists, such as Dr. Kristen Marhaver at CARMABI research station in Curacao, are also working on a kind of IVF for endangered corals—helping them grow more babies in order to repopulate reefs. 

Coral reefs can also benefit from a boost in their numbers provided by coral farming. Because they are colonial animals, a fragment from a coral colony can successfully regenerate into a new, independent, healthy colony of its own. The process is similar to taking a cutting from a bush to grow a new plant and can take many forms.

Staghorn coral farm. Photo credit:  The Nature Conservancy

Staghorn coral farm. Photo credit: The Nature Conservancy

For instance, The Nature Conservancy has launched an ambitious effort to restore one million corals in the US Virgin Islands and Florida. Working in partnership with Mote Marine Lab, the effort will help restore corals and further research into coral strains that have natural resistance to climate change. Meanwhile, on the other side of the globe, the Karya Segara venture off Indonesia grows corals to sell to the aquarium trade, providing artisanal fishers supplemental income in exchange for giving up destructive fishing practices, such as dynamite fishing. Corals are also out-planted onto destroyed reefs. The coral farms have also attracted tourists who will pay to swim among the baby coral "crops."  

Farming corals offers a way to rebuild degraded reefs at a faster pace than nature can do on its own. And while farming could never suffice to restore a reef at the scale of the Great Barrier Reef, it can work to help rebuild populations of locally endangered species. 

I remain hopeful regarding the future of coral reefs, but it is an optimism laced with a healthy dose of reality that time is running out. This year, the corals of the Great Barrier Reef showed they are doing all they can to provide for the future of the largest living structure on the planet—now it's our turn to do the same.  


Put More Blue into Black Friday

On the eve of the biggest shopping day of the year, here are a few ways you can use your dollars to support healthy (and sex-friendly) oceans while still satisfying all the different desires of those on your holiday shopping list: 

'Shopping Spree" Photo credit:  Damian Gadal , Flickr Creative Commons

'Shopping Spree" Photo credit: Damian Gadal, Flickr Creative Commons

For the Foodies:

These three books, all by sustainable seafood chef, Barton Seaver, will keep any foodie busy dishing up tasty, sex-friendly seafood dishes all year round:

  • For Cod and Country: "...Seaver introduces an entirely new kind of casual cooking featuring seafood that hasn't been overfished or harvested using destructive methods."
  • Two If By Sea: "Barton Seaver's second, seminal book on seafood cookery offers more than 150 new mouthwatering recipes, including entrees, salads, appetizers, soups, pastas, stews, sides, and sauces."
  • Superfood Seagreens: A Guide to Cooking with Power-packed Seaweed. "With benefits ranging from weight loss and increased energy to overall good health, no wonder sea greens (such as kelp, dulse, wakame, and alaria) are poised to become the next superfood craze."

Finding the ingredients to cook with can be as much as a challenge as finding a good recipe. The following companies are working to make sustainable, trustworthy seafood available to consumers around the country (and they are both founded and owned by women, which is rad):

Salty Girl Seafood: fresh-frozen and smoked seafood products. "Every fish we source is wild caught and undergoes rigorous evaluation to ensure that the specific fishery, gear type, species, and location meet our sustainability standard." 

LovetheWild: sustainable seafood and sauces in ready-to-cook packaging. "We bring you fish from fishermen and fish farmers we know and trust. They care about the planet as much as you do."  (A particularly good option for those who wish they were foodies, but perhaps are a bit intimidated by the thought of prepping a seafood feast...).

For the Fashionistas:

Patagonia: This year, Patagonia has committed to giving 100% of all proceeds from its Black Friday sales to environmental NGOs.  With products made from recycled products and eco-friendly business practices, this company gives back to the planet everyday. 

Waterlust: With patterns inspired by the sea and its inhabitants (whale shark leggings anyone?!) this company creates sustainable products that support ocean science and education programs.

For the Adventurers and Travelers:

The following countries have all passed legislation that promotes more sex-friendly seas. By spending your tourism dollars here, you support the governments and communities that support the sea. 

The Cayman Islands: stay tuned for a more detailed blog about the great developments in this small Caribbean nation but the short story is this: In mid-August, based in large part on the science produced by REEF's Grouper Moon Project, the government passed a series of regulations to protect the endangered Nassau Grouper. One of these regulations is to ban take, possession and sale of Nassau grouper during their spawning season, from December to April-- a very sex-friendly move. 

Palau: This tiny island nation made big news last year when it protected 80% of its ocean territory, banning all extractive activities including fishing. Large reserves such as these help protect spawning habitat for many species and migration corridors for those animals that migrate to mate. 

Blue Halo Initiative: An effort supported by the Waitt Institute, the following countries have or are working to create island-wide marine management plans that are firmly rooted in up-to-date science and are community-driven.  Included in these management plans are considerations for the reproductive habits and needs of local marine species. 

  • Barbuda
  • Montserrat
  • Curacao

For the Bookworms:

Norman the Nurse Shark (for kids): this wonderful story by Jillian Morris, founder of Sharks4Kids, introduces many charismatic marine species to children, as well as some of the threats they face. Proceeds help support ocean education programs run by Sharks4kids around the world. 

American Catch: another great by author Paul Greenberg, this book provides fantastic insight into how we (as in, the USA) have squandered much of our precious fisheries resource, and what we can do to better support local, sustainable fisheries in our coastal waters. 

Sex in the Sea: yeah, I know, tooting my own horn. But I really do think it is a great gift for the water/nature-lover, the science enthusiasts, the teachers, the teenagers, and the know-it-alls on your list. Also good for that impossible uncle that you never know what to get. Educational, a bit surprising, and humorous, it makes for a fun read...or so I've been told. 

In honor of: 

One of my favorite ways to give at the holidays is to donate to organizations that are out there doing the good work to serve those most in need, and those without voice—including marine life. The following are just a few examples of some great non-profits that now, more than ever, could use a boost. Donate in the name of someone you care about to help create change. 

Ocean Discovery Institute: a small non-profit that "uses ocean science to empower young people from underserved urban communities." This organization is helping to build the next generation of ocean leaders—and making sure they are as diverse as the seas. 

Science and Conservation of Fish Aggregations (SCRFA): this science-based non-profit works to promote understanding and protection of fish spawning aggregations around the globe. 

National Resources Defense Council (NRDC): this non-profit has a strong oceans program that tackles several of the issues threatening safe sex in the sea, including noise pollution, climate change, and overfishing. one of the leading grassroots organizations fighting climate change—which is one of the biggest threats to successful reproduction of marine life, especially for coral reefs. 


The Secret Lives of Horseshoe Crabs- Guest Blog on Cool Green Science

Horseshoe crabs coming ashore to get it on. (c) Gregory Breese/USFWS

Horseshoe crabs coming ashore to get it on. (c) Gregory Breese/USFWS

The lapping waves and silent dunes of the Delaware Bay shoreline create a perfect backdrop for a moonlit summer stroll. But a few weeks ago, this beach was not nearly so quiet. Instead, the silver light of the full moon shone upon jostling crowds of horseshoe crabs.

“If the crabs were rocks,” says Moses Katkowski, marine conservation coordinator with The Nature Conservancy, “you could walk on their backs the entire stretch of beach and never touch the sand.”

Every year, they emerge from the depths for one reason and one reason only: sex.

Lots and lots of sex.

Long before Roman emperors threw outlandish orgies, horseshoe crabs—contemporaries of the first sharks, wooly mammoths, and now us—have been making annual migrations to the shore to forge the next generation...

Read full post featured on The Nature Conservancy's Cool Green Science blog.