This Hermaphroditic Sea Slug Bits Herself or Her Partner’s Penis During Sex

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In 2013 a group of Japanese scientists published an article depicting a sea slug with a disposable penis. Strange as it may seem to us, the concept of the detachable penis comes as no surprise to malacologists, which is what we call people who study slugs, snails, octopuses and other soft creatures.

In fact, I was thinking about the sex of snails a few weeks ago because our department held a taxonomic workshop where, among other expert presentations, a malacologist named Winston Ponder told us how to tell one gastropod from another. I learned for the first time that many snails have an external cephalic penis.

Think about what that means. A cephalic penis has no head, it grows out of your head. The snail penis looks like a fleshy dreadlock growing right next to their wide, wide eyes. At least they can see what they’re doing when the deed is done.

And suddenly I realized that snails must wear their penis on their head, because if it was hidden inside their shell, how would they use it? I wondered why I hadn’t thought of that before, when Winston was enlightening us on other anatomical quirks of our mollusc brethren.

You’d think two days of this stuff would send a roomful of humans into a fit of giggles, but taxonomists are made of tough stuff. This fact is that people who name and describe species spend a lot of time illustrating and discussing the shape of sex organs. (Unless you’re working on fish or birds, but that’s another story.)

Sexual organs are often the most distinguishing characteristic of a species. We often know plants by their flowers. Although you can recognize a rose bush just by its foliage, you can’t be sure of the exact type of rose until the flowers come out. For some reason, you’re not ashamed to rip out that sex organ and put your nose in it. So don’t judge scientists for putting snail bites on slides and categorizing them.

Gastropod penises come in different shapes, including the bilobed or bilobed version. Some snails have internal penises and others are appealing. It’s a word that means “without a penis”. They would be the snails without a bite. You might be tempted to call them girls, except that they all are, even those with penises. Indeed, snails and slugs are hermaphroditic, with completely functional, and often multiple, female and male reproductive parts.

I wanted to ask Winston Ponder if call species were considered “lower” gastropods because as humans we believe that anything without a penis cannot be highly evolved. I never got into it, but my head was inexplicably full of questions about snail sex, which is perhaps why the latest slug sex news caught my eye.

Slugs are snails that have lost their shells, allowing them to put their penises back where they belong, that is, away from their heads. When slugs have sex, they line up from head to toe because their male and female parts are always on the same side of their body. The logistics of two penises and two vaginas create a complex set of sexual politics, including something quite sinister about earth slugs called naming.

The Greek prefix a- means without, and phallate means having a penis, so it makes sense that call snails don’t have a penis. The Greed prefix apo- means separation, so apophallate slugs once had a penis but somehow lost it. This seems particularly tragic in the case of the well-endowed banana slug, whose scientific name means “big penis.” The truth is, apophallate is a fancy word for a violent act.

Sometimes land slugs get stuck during sex. When they can’t separate after sex, according to Wikipedia“a slug gnaws either its own penis or that of its partner”.

I find that hard to believe.

Even a slug will be reluctant to gnaw on its own penis when it could bite another slug’s penis instead. The alternative is a level of altruism I can’t believe: loving slugs protect their partner by making the ultimate sacrifice. I prefer to believe this quote from a real malacologist who considered the gain at issue:

“The apophallated slug…cannot regrow its penis and is now forced to be a female and compelled to offer eggs. It may be that the castrator can increase its reproductive success by locally increasing the density of females.

This raises the idea that although slugs start out with the gear to be male or female, they can be forced into the female role. Cultivating and nurturing eggs is an energetic burden, and if the decision of who becomes the male occurs during sex, then we have a veritable battle of the sexes.

Some tapeworms “penis fence”, meaning they fight their partner’s penis while trying to make contact with their own. The first to enter remains the male, while the other must carry and care for their developing eggs. The Aussie species that does this isn’t just two-faced, it has two penises and a two-tailed sperm.

This brings us to the sea slug with the disposable penis. Chromodoris reticulata is a sea slug only a few centimeters long, and when scientists brought specimens to the laboratory for observation, they were not surprised by the sight of two penises inserted into each other, but by the caused their penises to fall off about 20 minutes after sex. act.

By offering these individuals mating partners at various intervals, they learned that it took these slugs around 24 hours to regrow their penises. One individual was able to mate three times in three days, causing his (or her?) appendix to regrow each time.

The most famous detached appendage is the hectocotylus, or octopus penis, first described by Aristotle. Because it stayed inside the female, it was long thought to be a parasitic worm.

Argonaut octopus males are so small compared to females that scientists didn’t realize they were the same species for hundreds of years. They use their modified arm to transfer the sperm to the female, but it breaks and they never get it back. As a result, they only mate once in their lifetime.

While losing your penis isn’t unusual among molluscs, growing it back is a neat trick.

This article was originally published on The conversation by Susan Lawler at La Trobe University. Read it original article here.

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