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Under The Sea, Sex Is Slimy Business

Never threaten a hagfish. And if you do, watch out.

"When it's threatened or in danger or gets injured, it produces — very quickly — huge amounts of slime," says Ellen Prager, a marine scientist and educator. "In fact, they found that in just a few minutes, it can fill up seven buckets full of gooey, slimy gunk."

The hagfish isn't the only underwater inhabitant with unusual tactics for survival. In Sex, Drugs, and Sea Slime: The Oceans' Oddest Creatures and Why They Matter, Prager describes some of the craziest underwater activities that help ocean creatures stay alive, fight predators, find food and reproduce.

Consider The Lobster

There are more than 100 species of lobsters in the ocean, but the one Americans are probably most familiar with is the Maine lobster, a wide-clawed nocturnal creature with a propensity for urinating on potential mates.

"The male lobsters use [urine] aggressively, but the female lobsters shoot it as a Love Potion No. 9," says Prager. "She shoots when she comes up to a den that might have a male in it. She actually seduces him with her pee and instead of clobbering her over the head with his claw, he says, 'Come in, come in' and gets all touchy-feely."

But before the female and male lobsters mate, the female sheds her shell.

"For the female lobster's private parts to become available, she has to molt," says Prager. "And then she becomes acceptable to the male."

Dominant males are routinely seduced into one-off sexual encounters while female lobsters are generally more choosy, says Prager. Females can store a male's sperm for up to three years, using it to fertilize several batches of eggs.

Coral Reefs: The More, The Merrier

Prager has a unique view of marine life because she used to be the chief scientist at an underwater research lab in the Florida Keys. The lab, which sits underneath 60 feet of water, allows scientists to spend hours underwater studying the ocean without worrying about decompression.

Dr. Ellen Prager
Rodrigo Varela / University of Chicago Press
Dr. Ellen Prager

The warm and relatively shallow water provided a fertile ground for reef-building corals. The organism, which looks like rock, is considered an animal, plant and mineral. It also provides food and shelter for other marine life and can develop into some of the biggest biologic structures on the planet, says Prager. And just how do they build those structures?

Most coral reefs are what scientists refer to as "broadcasters." That means they release either eggs or sperm into the water, where they float to the surface, mix and become fertilized.

"So if you're a coral and you want to mix your eggs with the sperm of another coral of your species, [you must] release [them] at the same time," says Prager. "So coral reefs spawn synchronously throughout the world. All those corals release their eggs and sperm at the same time."

Prager says she's witnessed the synchronized release of eggs and sperm while on night dives.

"It looks like an undersea snowstorm," she says. "The eggs look like little tiny pink balls and they all start floating up. And coral spawn is yummy fish food so worms and other things come to feed on it. It really [makes you think about] how active the ocean is."

Like the hagfish, corals also emit a mucuslike slime — dubbed "coral snot" — when disturbed.

"I will tell you from experience that if you disturb corals through something like drilling, [they] start to exude huge quantities of slime," she says. "You come up just covered in the stuff."

Ellen Prager has written several books about underwater life, including Chasing Science at Sea: Racing Hurricanes, Stalking Sharks and Living Undersea with Ocean Experts and Volcano: Iceland's Inferno and Earth's Most Active Volcanoes. She has worked at the Sea Education Association in Woods Hole, Mass., the University of Miami's Rosenstiel School of Marine and Atmospheric Science, and the National Undersea Research Center in the Bahamas. Prager has a Ph.D. from Louisiana State University and was chairwoman of the Ocean Research and Resources Advisory Panel for the U.S. government.

Interview Highlights

On the volcanic sexual activity of sea sponges

"A lot of the sponges release their sperm into the water. Other sponges will basically suck in that sperm and fertilize their egg. It looks like smoke coming out of the sponges and you look at it and go, 'What the heck is going on?' and they're broadcasting sponge sperm."

On the transgendered parrotfish

"If you have a harem of parrotfish — a group of female parrotfish, let's say — and it has one dominant male. Something happens to the dominant male and it dies. Amazingly, within several weeks, one of those females can change to a male. And, in fact, some of them change to what we call supermales — [and] become big and extremely colorful and aggressive. They then become the dominant male of the other female parrotfish in the harem. I like to say, 'It's not only transgender. It's transgender on-call.' "

On the well-endowed conch

"Turns out that in the conch, they call the penis its verge. The verge has been the thing of limericks and poems. The biologists know all about this. Not only is it exceptionally long, but because the queen conch is this really big snail, the male sidles up to a female on the seafloor and he has to get his verge outside of his shell and around and underneath the female shell. So that's why it's so long. But there's a little problem: When it's outside of his shell, crabs and eels are all too happy to take advantage of his vulnerabilities. Yum, yum, yum. Well, poor conch. But turns out, he loses one [and] he just grows another. He can regenerate his penis."

On why scientists are interested in kissing anglerfish

"The females are small, soft and they swim around trying to catch food. The males are dwarfs and their entire goal in life is to find a female. They swim around looking for the females. When they find them, I call it the 'never-ending kiss.' They bite into them and their lips get fused to the female and they end up living as a parasite on the female providing sperm. Scientists are really interesting in the immune system of anglerfish because the female's body doesn't reject the male."

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