Sea Slug Has Disposable Penis


A sea slug’s unusual mating behavior — it discards its penis after copulation, grows a new one, and has sex the next day — is reported in the latest issue of Biology Letters.

The sea slug, Chromodoris reticulata, is a type of soft-bodied marine mollusk, and its disposable penis is very rare in the animal kingdom.

As for what happens after sex … “The penis just falls off,” lead author Ayami Sekizawa told Discovery News.

Sekizawa, a researcher at Osaka City University, and colleagues made the discovery after studying C. reticulata individuals that they collected during scuba diving trips in shallow coral reef areas near Okinawa, Japan.

The researchers set up an experiment tank and watched as the sea slugs copulated 31 times.

These animals are “simultaneous hermaphrodites,” meaning each performs both the “male role” of donating sperm to a mating partner and the “female role” of receiving sperm from the partner simultaneously during copulation.

A typical mating episode involves two individuals touching each other with their genital orifices. They then “project” their penises and each insert them into the other’s vagina and start copulation. After a short time, one removes its penis from the partner. Later, the other mate removes its penis too.

Both individuals then crawl away, with their elongated penises still dangling. The sexual organs, which feature backward-pointed spines for possibly trapping rival sperm, would then suddenly sever from their bodies and float away.

Written By: Jennifer Viegas
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  1. In reply to #8 by AlGarnier:

    Well that solves the mystery of how Republicans evolved. If we could only Bobitize the Vatican residents with the option of stunting regrowth?!

    Vaticanites aren’t supposed to breed anyway, we really should nominate them all for a Darwin Award. If only we could work out some way of making their vile ideology die with them

  2. In reply to #2 by N_Ellis:

    In reply to #1 by QuestioningKat:

    My goodness, so many comments swirling around in my brain. Which one to choose? Disposable penis, hmm.

    How about: I used to have one of those.

    When your a female you could have as many penises as you want.

  3. In reply to #10 by QuestioningKat:

    When your a female you could have as many penises as you want.

    Queen honey-bees certainly take advantage of this!

    The sex organs of the male drone bees are also detachable – but —–
    Mating occurs in flight, which accounts for the need of the drones for better vision, which is provided by their large eyes. Should a drone succeed in mating he soon dies because the penis and associated abdominal tissues are ripped from the drone’s body after sexual intercourse.

    The drone penis is designed to disperse a large quantity of seminal fluid and spermatozoa with great speed and force. The penis is held internally in the drone (an endophallus). During mating, the organ is everted (turned inside out), into the queen. The eversion of the penis is achieved by contracting abdominal muscles, which increases hemolymph pressure, effectively ‘inflating’ the penis. Claspers at the base of the penis help to grip the queen. Mating between a single drone and the queen lasts less than 5 seconds, and it is often completed within 1-2 seconds. Mating occurs mid-flight, and 10-40m above ground. Since the queen mates with 12±7 drones, and drones die post-mating, each drone must make the most of his single shot.

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