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 phys.org

Photo credit: Adelaide university via phys.org

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.