Word of the Day: Apophallation

There are some things you just need to know, like the fact that Brontosauri never existed.

There are other things you really should know, like the fact that sea cucumbers breathe out of their butts (this little factoid comes in very handy if you have to quickly befriend a 10-year-old boy).

And then there are things you swear you could live without knowing, but let’s be honest—you’ve got questions and right now the most pressing one is probably “what does apophallation mean?”

It’s the deliberate amputation of the penis.

Gasp! I know, the horror, bear with me while I tell you about slug sex (and don’t you dare try to tell me that you’ve never wondered how it works).

Slugs (we’re talking about the big ones like the banana slug at right) are simultaneous hermaphrodites with both a penis and a genital opening on the right side of their heads. When two slugs get it on, they contort themselves into a yin yang-like position as they insert their penises into the other slug’s genital opening. They stay in this “embrace” for hours, both slugs acting as the fertilizer and the fertilizee, and then they separate.

Or try to separate.

Separating can be difficult after hours of entwinement and so they resort to what we might consider drastic measures: They chew off their partner’s penis—and then they eat it…and it’s captured on film, right here. (It’s really not that drastic since slugs retain a completely functional female reproductive system.)

Hence apophallation. (You’re right, you probably could live without knowing that, but wait, there’s more!)

The term apophallation seems to refer to slugs specifically, but they’re not the only animals to deliberately amputate male sexual organs. Orb-web spiders (Nephilengys malabarensis) also dabble in a little Bobbitism—and in their case, it’s a life-saving maneuver.

Male orb-web spiders, much like most males in the animal kingdom, want to produce as many offspring as possible. To do this, the male orb-web spider will have to mate with a female orb-web spider—and that’s not as pleasant as it sounds (for the male). The mating is short and when the female wants to end the copulatory event, she’ll start to eat her mate. BUT, if the male orb-web spider detaches himself from his palp (the spider equivalent of a penis), he can dash out of the female’s reach while his palp remains in his mate’s genital opening. By turning himself into a eunuch, the dude not only saves himself, he also maximizes his paternity.

Say what?

You’d think that once he ditched his palp the mating would be over, but it’s not. The palp continues depositing sperm while the male is running away. In fact, this process (known as remote copulation) results in greater sperm transfer and therefore greater offspring production than the typical orb-web spider method of old-fashioned copulation and sexual cannibalism.

Eunuch-izing himself gives the male some other advantages as well. The abandoned palp plugs the female’s genital opening, thus discouraging other males from mating and minimizing sperm competition. The female can remove the palp, however, making this roadblock technique only about 75% successful. Of course, to attempt to mate with the female, an intact male would have to get to her—and, with a eunuch guarding her web (from a safe distance), this is a difficult task. In lopping off his palps,* that wimpy (but crafty) male transforms into a badass mofo who attacks any male who dares step onto his lady’s web. Kralj-Fiser et al. found that eunuchs were significantly more aggressive, agile** and all-around better fighters than intact males. And so he may be palp-less but he’s alive and those baby spiders will all be his, dammit!

*Males start with two. Full eunuchs were found to be feistier than half-eunuchs.

**They suspect that the increased agility may be due to the eunuch’s, ahem, lighter load as they no longer have to lug those big ol’ palps around.

Li, D., Oh, J., Kralj-Fiser, S., & Kuntner, M. (2012). Remote copulation: male adaptation to female cannibalism Biology Letters DOI: 10.1098/rsbl.2011.1202

Kralj-Fišer, S., Gregorič, M., Zhang, S., Li, D., & Kuntner, M. (2011). Eunuchs are better fighters Animal Behaviour, 81 (5), 933-939 DOI: 10.1016/j.anbehav.2011.02.010