Disposable Penises in Ten Hundred Most Used Words

There is not much to add to the whole story on disposable penises after Ed Yong wrote about it.  So being a big fan of the Ten Hundred Most Used Words challenge (Can you explain a hard idea using only the ten hundred most used words?), I decided it was time I give it a go…

Animals that are both man and woman at the same time often have strange ways.  In a crazy soft animal that lives in water, one will cut off its man parts after each love act. After one day it can do the fun dance again with a new man part.  To have enough man part to do it three times, the man part is pressed and rolled up inside.  Man parts that can be thrown away are only known from these soft animals that live in water.


Figure 1. The fun dance and man bits (love gun) in a soft animal from water. (a,b) Two soft animals putting their love guns into each others woman hot spots. (c,d) cut off man bits after the fun dance; the end of the man bit is really filled out. A group of man matter for half baby making (sp) on pointed parts of man part (d). (e) cover of man bit has many pointed parts! (f) man parts for half baby making are caught in pointed parts.

Actual abstract:

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 ‘dis- posable 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).

Actual caption:

Figure 1. Mating and morphology of the penis in Chromodoris reticulata. (a,b) Two individuals reciprocally insert their penis into the partner’s vagina. (c,d) Auto- tomized penes after copulation; the tip of the penis is swollen. A mass of sperm (sp) is attached to the thorny penis in (d ). (e) Surface of the penis is equipped with innumerable backward-pointed spines. (f) Sperm are entangled in the spines. Autotomized penis stained with haematoxylin after being air-dried on a glass slide. Arrows show the direction of penis insertion.

Ayami Sekizawa, Satoko Seki, Masakazu Tokuzato, Sakiko Shiga, and Yasuhiro Nakashima
Disposable penis and its replenishment in a simultaneous hermaphrodite
Biol. Lett. April 23, 2013 9 2 20121150; doi:10.1098/rsbl.2012.1150 1744-957X

Dr. M (1729 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, a National Science Foundation supported initiative. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (http://deepseanews.com/), a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web. His forthcoming book, Science of the South (http://www.scienceofthesouth.com/), connects cultural icons of South such as pecan pie with the science behind them.

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5 comments on “Disposable Penises in Ten Hundred Most Used Words
  1. Your version is certainly much more fun to read. My students would probably understand it better too ;)

  2. Great… just great… now that song will be stuck in my head ALL DAY!!

    When I think of a female critter making off with the man part of her partner, the argonaut comes to mind.

    And now I want to see The Life of a Male Anglerfish in Ten Hundred Most Used Words.

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