the world is awash in sperm

The Navanax sea slug is a sort of legend in its own lifetime according to zoologist Janet Leonard. It’s known as the “if you can’t eat it, mate with it” slug.

Navanax is a hermaphrodite: like many other species, it has the anatomy and the ability to be either male or female. And Navanax gets to choose between the genders over and over again–it never has to settle for one or the other.

The name of the mating game, after all, is to pass along the most DNA, and sperm cells, which are small, require far less energy to make than do the much larger eggs. Eggs are expensive, but the world is awash in sperm, says evolutionary biologist Eric Fischer. Accordingly, females make many fewer eggs than males make sperm. And while males try to spread their inexpensive, abundant sperm far and wide, females try to invest their precious and limited store of eggs carefully.

Janet Leonard has been peeping in on and videotaping Navanax sex for more than a decade now. And, she reports, it’s a curious affair. Every Navanax comes equipped with a penis on the right side of its head; a few inches behind is a genital slit that leads to an ovary. Mating begins when one slug follows the trail of another and comes up from behind. The first slug pokes its head under the other’s tortilla of skin, twisting around to position its penis near the other’s genital opening. The second slug responds to this courting by raising its tail and unwrapping the sheath of skin around its body. After the sperm has passed from the first animal to the other, the female swings around and begins nudging its penis toward the genital slit of the male. If all goes well, they exchange jobs.

The animals keep trading roles, four, five, or more times. Fittingly, it’s a sluggish affair. One round of copulation, Leonard sighs, can take five hours. One of the first things you learn working with these animals is patience.

Often chains of three or more mating animals will form with those in the middle acting as male and female simultaneously.

This is a video of a Navanax biting an Aplysia, not having sex. I’ve included it because the two researchers making the video get so damn excited… “Hold on, Lafonda… this is a beautiful thing… atta girl”


Published in: on March 8, 2010 at 7:12 am  Comments (37)  
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  1. I’m claiming bullshit on that first bit of advice, Hashish will not make you a poet, unless you using it on the girl instead of yourself.

    • Take it up with Louisa, Alex 😉

  2. Slug sex – very erotic, there is a clip of the event on youtube, it’s from the BBC’s Natural World with David Attenborough doing the vo.

    Fantastic story about Suzanne Lenglen

  3. Well, I do feel sticky, but I thought that was because of the humidity.

    • hahaha…. *snort*

  4. I thought the term dickhead was just a funny metaphor. And as a zoologist, I concur with your research and explanation nursie.

  5. Is it me or did one woman sound on the brink of orgasm toward the end of the video?

    • They’re getting pretty damned excited aren’t they?

  6. One round of copulation can take five hours, eh? And presumably that’s not including the time spent buying flowers, drinking red wine and playing Barry White CDs. I’m impressed.

  7. If we were built like that I suppose I’d have to explain why I was always scratching behind my ears ……

  8. The penis-on-the-head thing: this is why slugs don’t play football. You couldn’t have a forest of players going up to head the ball, all waving their dicks. And any team fielding Dwight Yorke would be 3-nil up before the first whistle!

    • Gives whole new meaning to “giving head”

  9. I love the title. At least the male get’s a breather after the first emulsion. Performing in that capacity is tough on anything.

  10. A world awash in sperm? Not quite, but I’m doing my best.

    • oh good for you headbang8 – you’re my hero 😉

  11. Five hours!

    Does that include foreplay?

  12. Five hours, I bet that jerrk Sting is jealous of that, tantric sex and all.

    As for Nvanazx, I wonder if there is a reference to it in a book I have call Ruise Ye Sea slugs which is an anthology of haiku on the subkject of Sea cucumbers and sea slugs…..

    Mighty Navanax
    Can copulate for ages
    penis on its head

    somehting like that anyway!

  13. God, just imagine how much easier life would be if you could switch genders. Sexual gratification would be much easier to come by. My 18-year old niece posted sperm recipes on my sister’s Facebook wall. My sister though it was hilarious but I didn’t see the humor in it. I’m just an old uncle.

  14. Re: Louisa May’s advice – sounds great until the effects of the hashish wear off. Then what are you left with? Hopefully, not a slug…

  15. Oh, Louisa, I never knew. But my yellow lab growing up once ate a sea slug. So often in the nature shows, the free flowing sperm in the ocean is refered to as “the soup of life.” Hmmm…

  16. Often chains of three or more mating animals will form with those in the middle acting as male and female simultaneously.

    This sounds like that disgusting thing footballers get up to with girls of low morals: donner kebabing I think it’s called.

    • Camilla, do you have a blog? there’s no link….

  17. I used to play an online game where you flew little ships around and shot at people. It was called “Sub Space.” When you killed someone, everybody got a message “X” killed by “Y” Where Y was the person killed, and X was the person who did the killing.

    As a result, a lot of people had strange names, like “His Own Stupidity.” So if “His Own Stupidity” killed Fred, the message everyone would get was “Fred killed by His Own Stupidity.”

    On of my nicks was “Stray Sperm.”

  18. Now wouldn’t you suppose that if women didn’t make it so dang hard to penetrate, there wouldn’t be such a huge need for so much sperm. And five hours… now that’s not bad.

  19. I had never heard of the Louisa Alcott connection to hashish. I ended up researching it and found a (rather awful) story by her. http://www.homemakerscorner.com/peril.htm

    • …. ok, I’m off to float down a green path, as noiseless as a cloud, with a smile on my lips….

  20. You had me at the word Lafonda! If ever a funnier name existed I’ll eat my undies… skids and all.

  21. The human male mechanics are a bit wanting in dignity. In ‘The Bed Sitting Room,’ Spike Milligan proposed that the male member should be on the right forefinger. And the lady parts be on the left shoulder. That way, when a gentleman gives up his seat on the bus he could tap her on the shoulder and say: “Excuse me, miss…”

    • I think Spike and Louisa had something in common

  22. I don’t know about the hashish part, but being half-Italian I’ve got more than enough ardour as it is.

  23. Freda and Fred are my parents names …. gosh I am so confused now are they one person??

  24. HAHAHAHAHAHAAHAHA! They named the thing LAFONDA!

  25. Sometimes i wish i were a hermaphrodite…..

  26. There was some operatic snail sex in that insect movie “Microcosmos”. Liberated as they are, I’m fascinated and a bit repelled by all this sluggish eroticism. It’s great to know that the Navanax slugs are both bi, hermaphrodite and polyamorous. If they ever invent a drug which produces those effects instantly, they could call it Navanax.

  27. I find it interesting that LM Alcott said such a thing. LOL. Switching genders sure sounds like fun… because occasionally, I do wish I was a guy.

  28. A chain of slug fuckin? Hilarious. Also, that video is hysterical.


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