DETACHABLE PENIS

February 13, 2013 9:41 AM

Sea slug sheds its penis after sex, scientists find. This happens all the time. It's detachable.
posted by ninjew (59 comments total)

Pimp nudibranch knows all about this.
posted by phunniemee at 9:43 AM on February 13, 2013 [6 favorites]

Does it light up?
posted by marienbad at 9:46 AM on February 13, 2013 [3 favorites]

"'We propose that the tissue at the spiral part of the penis is compressed and undifferentiated, gradually differentiating into the "next penis",' the team wrote."

Ah, high school.
posted by griphus at 9:49 AM on February 13, 2013 [2 favorites]

+1000 for the King Missile link.
posted by Chrysostom at 9:53 AM on February 13, 2013 [27 favorites]

I am so glad that I was not the only one who thought of the King Missile song after seeing this on the BBC World News site last night.
posted by PROD_TPSL at 9:58 AM on February 13, 2013 [6 favorites]

Although it strikes me that the Dead Milkmen's "Peter Bazooka" is basically "Detachable Penis" done better.
posted by Chrysostom at 10:02 AM on February 13, 2013

He wanted 22 bucks, but I talked him down to 17.
posted by jonp72 at 10:15 AM on February 13, 2013 [6 favorites]

In other animal penis news, the alligator has a permanent erect, practically free-floating, spring-loaded bungee penis. Look!
posted by ChuraChura at 10:17 AM on February 13, 2013 [3 favorites]

Completely unrelated to Detachable Penis but best King Missile song ever (NSFW)
posted by mcstayinskool at 10:20 AM on February 13, 2013 [1 favorite]

In other animal penis news

Now there is a phrase most of us just don't hear often enough.
posted by bondcliff at 10:20 AM on February 13, 2013 [2 favorites]

The day when Metafilter become nothing BUT ANIMAL PENIS NEWS.
posted by Kitteh at 10:22 AM on February 13, 2013

The nightmare fuel drill-bit that is the weevil penis.
posted by Artw at 10:22 AM on February 13, 2013 [1 favorite]

Are you not subscribed to Lower Zoology Illustrated?
posted by griphus at 10:22 AM on February 13, 2013 [1 favorite]

Have detachable penis, will travel
posted by Blazecock Pileon at 10:23 AM on February 13, 2013

This news may alarm Mrs. Bellman.
posted by The Bellman at 10:23 AM on February 13, 2013

Have detachable penis, will travel

Don't you mean 'will mail'?
posted by Think_Long at 10:29 AM on February 13, 2013

Look, guys. I've been doing my best here to make metafilter only about animal penises. I'm glad others are finally stepping up to the challenge!
posted by ChuraChura at 10:30 AM on February 13, 2013

Needs more Ze Frank.
posted by briank at 10:30 AM on February 13, 2013

Just wanted to make sure there was a King Missile reference. Nothing to see here, move along.
posted by haunted by Leonard Cohen at 10:30 AM on February 13, 2013 [2 favorites]

The slug Judy Blume novels write themselves.
posted by biffa at 10:31 AM on February 13, 2013

After sex? That's nothing. Some Orb Weaver spiders detach that thing halfway through and run away to avoid being eaten by their mate.
posted by yellowbinder at 10:31 AM on February 13, 2013

"'We propose that the tissue at the spiral part of the penis is compressed and undifferentiated, gradually differentiating into the "next penis",' the team wrote."

If you can't have a penis,
Then ha'penis will do.
If you can't have ha'penis,
Then God bless you.

God bless you, sea slugs, God bless you!
If you can't have ha'penis, then God bless you!

everybody sing!
posted by GenjiandProust at 10:31 AM on February 13, 2013 [8 favorites]

I'm glad others are finally stepping up to the challenge!

Become a member now, with only a small donation!
posted by Blazecock Pileon at 10:32 AM on February 13, 2013 [1 favorite]

The actual paper is open access and short:

Disposable penis and its replenishment in a simultaneous hermaphrodite
Although it is often thought that sexual selection is weaker in simultaneous hermaphrodites than in gonochorists, some simultaneous hermaphrodites exhibit bizarre mating behaviour. In the simultaneously hermaphroditic nudibranch Chromodoris reticulata, we found a peculiar mating behaviour, wherein the nudibranch autotomized its penis after each copulation and was able to copulate again within 24 h. To have sufficient length to be replenished for three copulations, the penis is compressed and spiralled internally. No other animal is known to repeatedly copulate using such ‘disposable penes’. Entangled sperm masses were observed on the outer surface of the autotomized penis, which is equipped with many backward-pointed spines. There is a possibility that the nudibranch removes sperm already stored in a mating partner's sperm storage organ(s).

1. Introduction

Several hypotheses have been proposed regarding the evolutionary conditions promoting simultaneous hermaphroditism [1]. The most prevalent hypothesis postulates that low population density and low mobility favour simultaneous hermaphroditism, conditions where sperm competition may be of minor importance. However, hermaphrodites frequently live under high-density conditions. Furthermore, multiple mating is common in many species [2], indicating that sperm competition may be as important in hermaphrodites as it is in gonochorists. Consistent with this, many hermaphrodites have evolved sperm storage organs or specialized means of digesting excess sperm [3], and a cryptic choice may be performed by the ‘sperm recipient (female role)’ [4,5].

Because almost all nudibranchs (Gastropoda: Opisthobranchia) are simultaneous hermaphrodites whose female reproductive organs store allosperm donated from mating partners, there is a high potential for sperm competition. Nudibranchs perform both the ‘male role’ of donating sperm to a mating partner and the ‘female role’ of receiving sperm from the partner simultaneously during copulation. Nudibranchs generally have two sperm storage organs in the female reproductive system, a bursa copulatrix and a seminal receptacle, and they can digest allosperm in the bursa copulatrix (gametolytic organ) [6]. This enables the possibility of post-copulatory female choice or cryptic female choice. Among nudibranchs, the morphology of reproductive organs is extremely diversified, and the configuration and connection of each pouch differ among groups [6]. However, there have been few detailed studies of the relationship between mating behaviour and the morphology of reproductive organs, particularly from the perspective of sexual selection, and little is known about sperm competition in nudibranchs. In this study, we describe an extremely peculiar mating behaviour, wherein a nudibranch autotomizes its penis after copulation and can copulate again within a day, and we discuss the advantage of this behaviour in sexual selection.

3. Results

(a) Penis autotomy
We observed 31 reciprocal copulations. After each copulation, the penes were elongated and autotomized. In a typical case, two individuals encountered and touched each other with their genital orifices and then projected their copulatory apparatus after they separately crawled on the bottom and side of an experimental tank. After two individuals touched with the right side of their bodies, and adjusted the tip of the projected genitalia of the other, each inserted its penis into the partner's vagina and started copulation. After tens of seconds to a few minutes from the beginning of copulation, they pushed away the partner using the buccal bulb and separated with their penes stretched and elongated (figure 1a,b). When both individuals advanced further, one individual removed its own penis from the partner's vagina. After a few minutes, the other individual also removed its penis and their copulation ended. After copulation, both individuals crawled with their elongated penes remaining outside the body. Finally, they autotomized and discarded their penes (figure 1c). The mean duration of copulation was 9.50 ± 5.05 min (mean ± s.d.; n = 31). In each observation of copulatory behaviour, C. reticulata exhibited penis elongation and autotomy. Penis autotomy occurred 20.57 ± 7.04 min (mean ± s.d.; n = 9) after unplugging the penis from the partner's vagina.

(b) Remating
Behavioural observations (n = 108) revealed that C. reticulata needed approximately 24 h after the previous copulation to copulate reciprocally. When we paired a focal individual that had copulated less than 9 h before with another individual that had been isolated for 24 h or longer since the last copulation, the focal animal never copulated reciprocally and only eight copulated unilaterally in the female role (n = 47; table 1). Focal animals copulated reciprocally (n = 19), or unilaterally in the male role (n = 7), 22.4 h after the first copulation or later. In one case, we observed three successive copulations each separated by approximately 24 h.

(c) Morphology of autotomized penes and reproductive organs
The surface of the autotomized penis was equipped with numerous backward-pointed spines (figure 1e). The tip of the autotomized penis was somewhat swollen (figure 1c,d), and sperm were entangled in the spines (figure 1f). In some cases, a sperm mass was attached to the penis (figure 1d).
When the vas deferens was fixed 24 h or later after copulation and observed in wholemount, the inner duct of the middle region of the penis was compressed and coiled loosely (figure 2; n = 4). Individuals that had been fixed immediately after copulation had no spiral part of the penis (n = 3). The average length of the internal penis, including the spiral part, in cleared samples was 30.7 ± 10.0 mm (n = 4). The average length of an autotomized penis was 10.9 ± 1.5 mm (n = 10).

The arrangement, size and shape of the cell nuclei differed among the proximal spiral part of the internal penis, the distal part near the genital orifice of the internal penis, and the autotomized penis. Although the distal part and the autotomized penis had similar characteristics, the proximal part was different from the two regions. While the area of the nuclei significantly increased in order from the spiral part (60.6 ± 14.3 μm2; average ± s.d., n = 32), to the distal part (90.9 ± 17.1 μm2, n = 31) and autotomized penis (131.7 ± 30.5 μm2, n = 36) (p < 0.05, Steel–Dwass test), the cell density increased in reverse order (see the electronic supplementary material, figure S2).

4. Discussion

Although the penes of individuals that had been fixed and cleared at least 24 h since their last copulation had a spiral structure, those that had been fixed immediately after copulation did not. This suggests that the spiral structure is important in the autotomy and replenishment of the penis. On the basis of the average length of the internal penis, including the spiral structure, and that of the autotomized penis, C. reticulata penes were sufficiently long for at least three copulations. This corresponds with the observation of an individual that copulated three times over three consecutive days. The shapes and arrangements of cell nuclei were similar between the distal part of the penis and the autotomized penis, suggesting that only the distal part of the internal penis is available for copulation as the ‘next penis’. The spiral part of the internal penis appears unready for immediate copulation. Since cell density in the penis decreased and nucleus size increased towards the distal part of the internal penis, we propose that the tissue at the spiral part of the penis is compressed and undifferentiated, gradually differentiating into the ‘next penis’. When the distal part of the penis elongates to be used for copulation, part or all of the spiral structure seems to be uncoiled at the same time. After the penis is autotomized, it may need approximately a day for the spiral structure to be available for copulation.

The surface of the penis in C. reticulata was covered with numerous small, backward-pointed spines, and a large amount of sperm was entangled in the spines. One possibility is that C. reticulata performs sperm replacement using the thorny penis in the same manner as some damselflies, notably Zygoptera, such as Calopteryx maculata [7], which use a hook-shaped structure located at the tip of the male copulatory organ to remove the allosperm of previously copulating males already stored in a copulatory pouch [8]. Damselflies remove allosperm by voluntarily moving the hook-shaped copulatory organ. However, the penis in nudibranchs is not a muscular organ, as shown in the electronic supplementary material, figure S3, and thus it is impossible to move each spine voluntarily in C. reticulata. Another possibility is that excess sperm from the current donor was pushed out by the recipient and was attached to the penis. DNA analysis of the removed sperm is needed to verify its origin. The transformation and extension of the penis to insert deep into the copulatory pouch, and the development of backward-pointed spines, make it difficult for the penis to be withdrawn. This difficulty must be the essential reason for the particular penis autotomy.

Although various animals are known to autotomize parts of the body, only a few animals have been found to autotomize their penes or male reproductive appendages. For example, the hectocotylus of Argonauta [9] and the pedipalp of some orb-weaving spiders [10] are autotomized to facilitate transferring spermatophores. Furthermore, a periwinkle [11] sheds its penis after its reproductive season, probably to save the cost of maintenance. The reproductive organ is used differently in these animals compared with nudibranchs. Apophallation in Ariolimax [12] would instead have a common point that this land slug and C. reticulata sacrifice their penes under competitive conditions with rivals in reproduction. Different from C. reticulata, penis loss in Ariolimax is caused by the mating partner, and the land slug cannot regenerate its penis. Chromodoris reticulata may compensate for the short-term cost of decreased reproductive opportunities caused by the loss of a penis with the reproductive advantage gained by sperm displacement under severe sperm competition. They further minimize the loss of reproductive opportunities by preparing the ‘next penis’ using the spiral structure to shorten the interval until the next possible copulation. Thus, the ‘disposable penis’ in C. reticulata provides an example where sexual selection is as important for simultaneous hermaphrodites as it is for gonochorists.

posted by Blasdelb at 10:33 AM on February 13, 2013 [6 favorites]

This post was deleted for the following reason: We've kind of had a lot of animal-penis posts lately and this feels a bit like web-drama-for-web-drama's sake.
posted by Curious Artificer at 10:33 AM on February 13, 2013 [1 favorite]

Also FOUR PRONGED ANTEATER PENIS. That's exactly what it says it is. Don't go complaining to me if it grosses you out or gets you in trouble at work.
posted by yellowbinder at 10:34 AM on February 13, 2013

After sex? That's nothing. Some Orb Weaver spiders detach that thing halfway through and run away to avoid being eaten by their mate.

Respect.
posted by The Bellman at 10:34 AM on February 13, 2013 [6 favorites]

Some Orb Weaver spiders detach that thing halfway through and run away to avoid being eaten by their mate.

#goodwithtartarsauce
posted by Blazecock Pileon at 10:36 AM on February 13, 2013

Though echidnas are sometimes called spiny anteaters, they are marsupials, not placental mammals, and not closely related to regular anteaters. They do have pretty great penises, though.
posted by ChuraChura at 10:37 AM on February 13, 2013

Metafilter: All animal penis, all the time.
posted by Billiken at 10:38 AM on February 13, 2013

Ha yeah I had it in my "file away for later trivia usage" iPhone note as echidna but on googling was presented with Spiny Anteater on video and simplified. Cheerfully corrected.
posted by yellowbinder at 10:42 AM on February 13, 2013

DAH dah dah dah dah dah dah dah
DUH duh duh duh
DEH deh deh deh
DAH dah dah dah dah dah dah dah
posted by brain_drain at 10:43 AM on February 13, 2013

VOM
posted by Lipstick Thespian at 10:46 AM on February 13, 2013

la petite mort
posted by KMB at 10:47 AM on February 13, 2013 [1 favorite]

Although it strikes me that the Dead Milkmen's "Peter Bazooka" is basically "Detachable Penis" done better.
posted by Chrysostom at 10:02 AM on 2/13
[+] [!]


Metafilter: Your favorite modular phallus song sucks.
posted by dr_dank at 10:56 AM on February 13, 2013 [2 favorites]

MetaFilter: Only About Animal Penises.
posted by InsanePenguin at 11:05 AM on February 13, 2013

Sure, my Ze Frank slug sex post was deleted and this one stays???!!!!...sheesh.... (I do see someone snuck Ze in upstream there, good work! Don't tell the mods that this was all a way to get around the original deletion of the Ze post... what? I've said too much?? Damn. )
posted by HuronBob at 11:08 AM on February 13, 2013 [1 favorite]

"Though echidnas are sometimes called spiny anteaters, they are marsupials, not placental mammals, and not closely related to regular anteaters. They do have pretty great penises, though."

I thought you said enchiladas, and that made no sense at all.
posted by HuronBob at 11:09 AM on February 13, 2013 [2 favorites]

In a typical case, two individuals encountered and touched each other with their genital orifices and then projected their copulatory apparatus after they separately crawled on the bottom and side of an experimental tank. After two individuals touched with the right side of their bodies, and adjusted the tip of the projected genitalia of the other, each inserted its penis into the partner's vagina and started copulation.

what
posted by ninjew at 11:29 AM on February 13, 2013 [2 favorites]

Well this is what it made me think of. (NSFW)
posted by XMLicious at 11:32 AM on February 13, 2013

Metafilter: (a) Penis Autonomy
posted by computech_apolloniajames at 11:47 AM on February 13, 2013

what

They are hermaphrodites.
posted by Tsuga at 12:33 PM on February 13, 2013 [1 favorite]

King Missile's younger brother Faceboy is a frequent guest on the Keith & The Girl comedy/talk show podcast. Often appearing with Reverend Jen.

He's told several amusing stories about how KM used to convince him various fictional things were true when they were kids, things that he would then go on to repeat as fact in school and sometimes even use in school projects.
posted by NoAccount at 12:38 PM on February 13, 2013

Meanwhile, Nicolas Cage skims this thread to determine which animals not to eat today. handily linked from Telegraph article
posted by obscurator at 12:45 PM on February 13, 2013

Did somebody call for a detachable penis? One that lights up even!
posted by DreamerFi at 1:35 PM on February 13, 2013

I remember seeing them live (the band, not the sea slug), and while Martin Scorsese was a great song, that night belonged to Cheesecake Truck.
posted by Ghidorah at 3:10 PM on February 13, 2013

Hard-on.
Hard-off.
posted by Kabanos at 3:10 PM on February 13, 2013

Don't get me started on Banana slugs - Apophallation [with video].
posted by unliteral at 3:22 PM on February 13, 2013

Is this where an evening devoted to listening to King Missile songs starts? This feels like the place where an evening devoted to listening to King Missile songs starts.
posted by Golfhaus at 3:26 PM on February 13, 2013 [1 favorite]

And then there is the male anglerfish, who doesn't have a penis - he becomes a penis, basically. (Well, a set of gonads. But whatev.)
posted by EmpressCallipygos at 3:32 PM on February 13, 2013

I took it home, washed it off, and put it back on.

(No idea why I felt the need to post that other than I've always liked that line.)
posted by InsertNiftyNameHere at 4:28 PM on February 13, 2013

Now I'm imagining a pseudo-raunchy Pixar movie starring a sea slug of, um, diminutive stature who, after having sex one night with a mysterious ladyslug, grows a new penis that's HUGE. The rest of the movie is him getting into all sorts of sexual hijinks where he wants to use his giant penis, but won't because he knows it'll fall off and then he'll be back to having a tiny dick.
posted by chrominance at 4:51 PM on February 13, 2013

(er, except I guess sea slugs are hermaphroditic, so it's not really a man-slug and a lady-slug, forgive my heterocetricity)
posted by chrominance at 4:52 PM on February 13, 2013

In a typical case, two individuals encountered and touched each other with their genital orifices and then projected their copulatory apparatus after they separately crawled on the bottom and side of an experimental tank. After two individuals touched with the right side of their bodies, and adjusted the tip of the projected genitalia of the other, each inserted its penis into the partner's vagina and started copulation.

I... I... think I used to share an apartment with those guys.
posted by Multicellular Exothermic at 5:13 PM on February 13, 2013 [2 favorites]

Wrong post to read through the comments whilst eating dinner.
posted by PuppyCat at 5:16 PM on February 13, 2013 [1 favorite]

Yeah, PuppyCat, I hear you.
*snigger*

So, yellowbinder, are you sure that anteater doesn't have a HAND at the end of its penis? The very thought terrifies me.
posted by BlueHorse at 7:05 PM on February 13, 2013

Meanwhile, sea squirts eat their own brains. I guess a sea slug/sea squirt hybrid, if such a beast could be, would eat it's own... hmm.
posted by homunculus at 10:57 PM on February 13, 2013

I... I... think I used to share an apartment with those guys.

Perry! Perry!
posted by FatherDagon at 2:33 PM on February 14, 2013 [1 favorite]

Yellowbear, my smugness has come to bite me in the ass. Turns out echidnas aren't marsupials, they're monotremes! Just like platypuses!
posted by ChuraChura at 9:37 PM on February 14, 2013