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Spider Penis Detaches To Allow Escape From Carnivorous Mates

Spider Penis

First Posted: 02/ 1/2012 9:28 am Updated: 02/ 1/2012 9:28 am

Jennifer Welsh, LiveScience Staff Writer
First Published 01/31/2012 07:24 PM EST

Sex can be dangerous, even deadly if your partner has plans to eat you. When the male orb-web spider has its first, and sometimes last, sexual encounter it has a trick up its sleeve: detachable genitalia which keep pumping even after their owner's moved on.

The orb-web spider Nephilengys malabarensis is sexually cannibalistic and the male has detachable genitals. These spiders have at most two chances to mate: They have a pair of sperm-transferring organs, actually called their "palps" but analogous to a penis, which detach from their bodies when they disengage from mating — either when the female pushes them away and possibly eats them or they successfully run away to risk death another day.

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  • Angler Fish

    It's almost impossible to catch a male angler fish. Why? They don't exist for very long. When a male angler fish is born, it is a tiny creature with no digestive system. As such, it must swim to find a female angler fish as soon as possible. When it does, it bites and releases an enzyme that removes a part of her flesh allowing the male to fuse. Soon it becomes nothing but a small bump on the side of its partner. This lump stores the sperm needed for fertilization when the female is ready to reproduce. <a href="" target="_hplink"></a>

  • Garter Snake

    When a female garter snake is ready to mate, it releases a strong sex pheromone that drives hundreds of male gartner snakes to her location. Once there, the snakes form an intertwined pile of slithering bodies, covering the female and attempting to mate with her at the same time. This not only provides the female with a vast plethora of potential suitors, but also warmth and protection during the process.

  • Hippopotamus

    Hippos might look lackadaisical, but don't be fooled. They're among the most dangerous animals in the world, and are highly territorial. During mating, the male will empty his bladder and bowels in the surrounding water and use his powerful tail to splash the fecal water at a female of interest. Skip to 1:35. <a href="" target="_hplink"></a>

  • Camel

    Male camels who are sexually aroused attract females through excessive salivation, covering their mouths in a drooling white froth. But that's not all: they also expel a pink sack from the roof of their mouths called the doula, which hangs out from the side of their mouths to attract females. Skip to 1:13 to see the mating ritual.

  • Manakin

    The manakin is a small bird with a startling, stage-worthy mating ritual; the Moonwalk.

  • White Fronted Parrot

    As a part of their mating ritual, the white fronted parrot kisses its partner much like two humans might - except without the beaks. But unlike the standard french kiss, the male parrot adds a secret ingredient: vomit. <a href="" target="_hplink"></a>

  • Bean Weevil

    The bean weevil's penis is covered in sharp spines. Its genitals severely damage the inside of the female's reproductive tract, a phenomenon known as "traumatic insemination." <a href="" target="_hplink"></a>

  • The Porcupine

    During courtship, porcupine males stand on their hind legs and spray their partners with urine. If a female is ready to mate she will then allow the male to mount. <a href="" target="_hplink"></a>

  • Honey Bee

    After ejaculation, the male honey bee's genitals break away from the body and lodge themselves inside the queen bee's reproductive tract. This acts as a plug that blocks any other worker bees from mating with the queen. This insurance, however, comes at a cost, as the male honey bee dies soon after. <a href="" target="_hplink"></a>

  • Praying Mantis

    The praying mantis is infamous for its mating ritual. During coitus a hungry or stressed female will bite off the head of its mate and use it for nourishment. Unlike common belief however, this form of "rough" mating only occurs less than a third of the time. Nevertheless, the male mantis takes a definite risk in each attempt at procreation. <a href="" target="_hplink"></a>

  • The Giraffe

    To check if a female giraffe is ready to mate, the male will nudge her behind with his head to induce urination. He will then taste the urine to see if she is in heat. If so, he will follow her around until she allows him to mount. Interestingly, females that find a male to be particularly attractive have been observed to urinate more. <a href="" target="_hplink"></a>

  • Argonaut

    Male argonauts have a specialized tentacle, known as a hectocotylus, that holds a ball of spermatozoa on the end. In the vicinity of a female, this tentacle actually detaches from its host and swims towards the prospective mate. <a href="" target="_hplink"></a>

  • Echidna

    The porcupine-like echindna has a four-headed penis. Even more surprising is the coordination between the heads; they work in pairs, with only one pair active at any one time. The other pair rests, in preparation for the next round of mating. <a href="" target="_hplink"></a>

  • Banana Slugs

    Banana slugs have extremely long penises, some as long as their own body length. As hermaphrodites, two slugs will form the arrangement shown above in order to try to fertilize one another. In some cases however, a penis can get stuck in the middle of the attachment, holding two slugs together. The solution? The other slug chews it off.

  • The Frigate Bird

    A male frigate bird inflates a large throat sack, a mating ritual that takes a lot of effort and some time. Once it inflates, the sack looks like a big pink heart. To complete the ritual the male will shake its wings and sing a mating call.

  • Hyena

    Female hyenas are at the top of the hyena hierarchy. They are the more aggressive and dominate sex. This is because young female hyenas produce androgens, a similar hormone to testosterone, which increases aggression and competitiveness. It also enlarges the genitalia, creating a seven inch clitoris, or pseudo-penis. This gets tricky when a male tries to mate, and means that rape is extremely difficult. What's more, females have to give birth through their enlarged clitoris, which can cause serious complications for the mother. Skip to 1:23 in the video to get a better look. <a href="" target="_hplink"></a>

  • Brown Antechinus

    The brown antechinus is renowned for its hyperactive sexuality. Male antechinuses have been known to engage in coitus for hours with a single partner, only to move onto another. Eventually the male dies, a sexual martyr, from a lack of food and rest.

For spiders this breakage of male’s sperm-transferring organ is common, says researcher Daiquin Li, of the University of Singapore, but it's usually just the tip.

"However, some spider species exhibit extreme genital mutilation or the 'eunuch phenomenon,' where males castrate their entire pedipalp(s) during copulation," Li, author of a new study on this process, told LiveScience.

Extreme sacrifice

This eunuch behavior is a pretty confusing concept to most researchers: They (like most men reading this) really couldn't think of a way that having a break-off penis could be a good thing. They previously thought that this full breakage was just a mistake (since what good, evolutionarily speaking, is a male unable to have sex?), but Li believes it must have some advantage for the male — possibly storing or transferring more sperm.

The researchers collected 50 virgin orb-web spiders — 25 each, male and female — from Singapore and raised them in the lab until they reached sexual maturity. They were mated in pairs by placing the smaller males into the female's web. The researchers recorded how long they mated, who stopped the mating, and how much palp broke off. Eighty eight percent of the time the spiders left the whole palp in the female.

After mating they left the palp in the female for different amounts of time (up to 20 minutes), then measured how much sperm was left in the palp and in the female's sexual organs. The researchers found that the detached genitalia continued to transfer sperm after sex ended.

"About 30 percent of sperm were transferred to the females before the palp breakoff, and about 70 percent of sperm were still left in the broken palp," Li said. "In our experiments, it took about 20 minutes to transfer about 85 percent of [the] sperm."

Prolonging sexytimes

This means that after the female frightens the male away, or eats him, his genitalia remain in place and can continue sending sperm her way, even long after sex is over — in the lab it took the females about seven hours to get the palp out. This elongated sperm transfer doesn't happen if they just break off the tip of the palp.

"This mate-plugging can partially serve as a plug to prevent other males" from mating with the female, Li said. "In addition, the eunuch males [if they survive] become more aggressive and guard the female so that this can make sure the sperm left in the severed palp can be transferred to the female after breakage," probably leading to better success at becoming a father, even in the afterlife.

Spiders aren't the only species to Lorena Bobbit their own genitals, and Li thinks the same sperm-transfer bonus may apply in other species, as well: "This may apply to other spider species and other animals in which males castrate their genitals, for example, in fire ants, ground beetles, scorpions and cephalopods," he said.

The study will be published tomorrow (Feb. 1) in the journal Biology Letters.

You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

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