The perfect music. The soft lighting. A reservation at the city’s hottest restaurant. This is the stuff of Valentine’s day...on land. Under the sea, dating and mating games take on a bit more flare.
The following “sex-sea” stories from Sex in the Sea highlight the magic and mystery of reproduction in the ocean, and the unexpected ways people are managing to disrupt romance in the deep. We are all far more intimately connected with the intimate lives of marine life than we realise – for better and for worse. For better, because the bounty of the sea, driven by lots of successful sex, provides us with food and medicine, spiritual and recreational value. For worse, because this relationship demands that we adjust management of our oceans to move from a prophylactic to a productive force for reproduction in the sea.
Lobsters: the Kinky Romantics
They may not look like it, but male lobsters are gentle lovers. Of course, they don’t easily display this romantic side. Female lobsters must engage in a week of foreplay and administer a powerful love potion to tame the beast every mating season. Luckily these shelled seductresses have discovered the perfect technique: repeated golden showers.
Squirt a healthy dose of urine into the male’s den a few days in a row and viola! He will invite that female in. At first, there’s lots of heavy petting with legs and antennae, but the male won’t get past second base until the female molts. Only after she slips out of her old shell and presents herself, soft-bodied and unable to stand, will sex be an option. In this most vulnerable state she can only hope her pee potion has worked its magic; that he’s excited for sex, and not an early lunch.
When all goes well, the male proceeds with a delicate consummation.
Positioning himself behind her, he ever-so-gently lifts her, his thin walking legs forming a hammock for her body. He rolls her over, bringing her belly to belly with him. In this missionary position, the male inserts his manly parts into her sperm receptacle, located at the base of her tail. A few thrusts and the deed is done. Days later, with new shell hardened, she leaves his den and the next female moves in. Lobsters say “I love you” with pee and serial monogamy.
Our connection: The complex courtship of lobsters depends on great chemistry between male and female. As climate change alters the saltwater environment via ocean acidification, chemical communication is bound to change. Lower pH can alter how receptor cells receive messages, as well as the content of the messages themselves. Other pollutants, such as oil, can mask these important scents altogether. For all these reasons, we must work to reduce our interference with the sexual chemistry of sea life. This includes strong action on climate change, as well as better management of coastal run-off.
Groupers: Orgies in the Ocean
Every February, caravans of Nassau grouper begin to stream southward along Little Cayman Island in the Caribbean. Researchers with the Grouper Moon Project, having tagged many of local reef residents, follow the pings of individual grouper as they descend for the bacchanalia – the one and only time they stray from their home territories each year.
Four days after the full moon, Little Cayman’s entire population of breeding adult Nassau grouper – all four thousand of them – will swim in a loose ball at the edge of the reef. As the sun sinks, their libido rises, and large females, bellies swollen with eggs, rocket upwards from the school. Reaching the top of their climb they let loose a cloud of eggs through which the trailing males streak, adding their own DNA to the mix.
Like an Old Faithful of fish, these geysers of sex erupt again and again from the main school. As dusk fades into night, the groupers relax their frantic forays. They remain quiet until the next day, when the sunset once again triggers its business time.
Our Connection: Showing up at the same time and place every year helps these normally dispersed fish find mates. But it also makes it easy for fishers to find fish – and wipe out an entire population. Better science and conservation of spawning aggregations is key to long-term success of species that group up for sex. As the saying goes: don’t come a-knocking when the beds a-rockin’…do this, and we’ll benefit from increasing populations and more fish throughout the year.
Sharks: Virgin Birth
Sometimes sex and reproduction don’t always go hand in hand. In some sharks, females can delay getting pregnant for up to four years after they last had sex. And in the smalltooth sawfish – which is not a fish at all, but a ray and close cousin of sharks – females are skirting the sex part altogether. That’s right, virgin birth is alive and well in the sea, and may be helping this endangered species squeak through some sparse times. Known as parthenogenesis, the technique allows a female to produce a genetically unique offspring without the addition of any male DNA. The message: this Valentine’s indulge your fancy, with or without a date.
Our Connection: Severely overhunted in the 20th C., female smalltooth sawfish may be turning to virgin birth as a result of not being able to find a mate. While this strategy can be a good stop-gap to keep the population humming, prolonged reliance on parthenogenesis ultimately lowers the genetic diversity of a population and skews the sex ratio (females can only give birth to females). Current bans on fishing have helped boost numbers and hopefully encourage more old-fashioned sex in this species.
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