Featured Research

from universities, journals, and other organizations

Spiders: Chastity Belts Protect Paternity

Date:
March 5, 2007
Source:
University of Bonn
Summary:
The fact that female wasp spiders have numerous sexual contacts is something which their male partners cannot prevent. What they can do, however, is ensure that no offspring ensue from these liaisons with their rivals: the male spiders simply place a chastity belt on their partner while copulating. The tip of their genital breaks off during intercourse, blocking the sexual orifice of the female spider.

A male wasp spider leaves the tip of his penis in the female wasp spider to prevent other males from fathering the female's offspring.
Credit: Copyright Frank Luerweg

The fact that female wasp spiders have numerous sexual contacts is something which their male partners cannot prevent. What they can do, however, is ensure that no offspring ensue from these tκte ΰ tκtes with their rivals: the male spiders simply place a chastity belt on their partner while copulating. The tip of their genital breaks off during intercourse, blocking the sexual orifice of the lady spider. Biologists from the universities of Bonn and Hamburg report on this amazing mechanism in the journal ‘Behavioral Ecology’ (vol. 18, pages 174-181, 2007).

Related Articles


When a male wasp spider discovers a potential partner, he turns her on by shaking her web. The female thereupon supports herself on her long legs on the web so that the male, who is much smaller, can then creep under her body. The rest works hydraulically: the tip of a transformed leg filled with sperm is inserted into the female’s sexual orifice – like a ski boot in its binding.

The female usually puts an end to the affair after a few seconds by attacking her partner and killing him if he does not escape in time. ‘When the male detaches himself from the female, in more than 80 per cent of cases the tip of his genital breaks off,’ the Bonn lecturer Dr. Gabriele Uhl says. ‘The tip then remains in the sexual orifice like a cork, blocking it.’

Together with her colleague Professor Jutta Schneider and the behavioural biologist Stefan Nessler (both now at the University of Hamburg), Dr. Uhl has been looking for a reason for this genital mutilation. ‘There are basically two hypotheses,’ she explains. ‘On the one hand detaching part of the genital organ could help the male to escape from the female’s murderous attack. On the other hand it might be a mechanism ensuring that paternity is maintained, preventing or impeding further copulation by the female.’

Genital tip as a ‘cork’

Even when giving her a quickie, a male transfers enough sperm to fertilise all his partner’s eggs. However, if a rival male then gets a look in, his sperm cells compete during copulation with those of his predecessor. ‘The detached tip might prevent subsequent intercourse, like a chastity belt,’ Jutta Schneider explains. ‘The first male would thereby ensure that all the egg cells were fertilised by him rather than his rival.’

In his diploma thesis at the University of Bonn, Stefan Nessler has been examining more closely which of the two hypotheses is correct. The result is that whether the tip broke off or not had no significant effect on the male’s survival rate – but it did affect any subsequent copulation with another male: when the sexual orifice was blocked, the game was over after only eight seconds; normally male spiders copulate for twice as long. ‘The results show that the blockage at least impedes copulation,’ Stefan Nessler emphasises. ‘Initial morphological studies show that the detached tip plugs the orifice so securely that the transfer of semen is probably largely excluded.’

The researchers have now been able to show that other species of wasp spiders also have this ‘plugging mechanism’. What they all have in common is that the female attempts to kill her partner during intercourse. ‘We presume that genital mutilation only makes sense if there is hardly any chance of further copulation anyway,’ Gabriele Uhl explains. ‘The males show maximum investment.’

Dr. Uhl’s diploma student Martin Busch is currently investigating a completely different strategy for preventing competitors from having intercourse: the dwarf spider produces a viscous secretion in its genital which it spurts after the sperm. This mucus plug blocks the female genital aperture so effectively that rivals can no longer copulate. Whether a mucus plug or the tip of the genital organ is used, the oviposition is unaffected by the ‘chastity belt’: ‘for that the females have a separate aperture,’ Dr. Uhl stresses. ‘In spider species with only one aperture for copulation and oviposition no such contraceptive strategies exist.’


Story Source:

The above story is based on materials provided by University of Bonn. Note: Materials may be edited for content and length.


Cite This Page:

University of Bonn. "Spiders: Chastity Belts Protect Paternity." ScienceDaily. ScienceDaily, 5 March 2007. <www.sciencedaily.com/releases/2007/03/070305102410.htm>.
University of Bonn. (2007, March 5). Spiders: Chastity Belts Protect Paternity. ScienceDaily. Retrieved March 5, 2015 from www.sciencedaily.com/releases/2007/03/070305102410.htm
University of Bonn. "Spiders: Chastity Belts Protect Paternity." ScienceDaily. www.sciencedaily.com/releases/2007/03/070305102410.htm (accessed March 5, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Thursday, March 5, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Praying Mantis Looks Long Before It Leaps

Praying Mantis Looks Long Before It Leaps

Reuters - Innovations Video Online (Mar. 5, 2015) — Slowed-down footage of the leaps of praying mantises show the insect&apos;s extraordinary precision, say researchers. Video provided by Reuters
Powered by NewsLook.com
Octopus Grabs Camera and Turns It Around On Photographer

Octopus Grabs Camera and Turns It Around On Photographer

Buzz60 (Mar. 5, 2015) — A photographer got the shot of a lifetime, or rather an octopus did, when it grabbed the camera and turned it around to take an amazing picture of the photographer. Jen Markham (@jenmarkham) has the story. Video provided by Buzz60
Powered by NewsLook.com
Ringling Bros. Eliminating Elephant Acts

Ringling Bros. Eliminating Elephant Acts

AP (Mar. 5, 2015) — The Ringling Bros. and Barnum & Bailey Circus is ending its iconic elephant acts. The circus&apos; parent company, Feld Entertainment, told the AP exclusively that the acts will be phased out by 2018 over growing public concern about the animals. (March 5) Video provided by AP
Powered by NewsLook.com
Raw: Tourists Visit Rare Grey Whales in Mexico

Raw: Tourists Visit Rare Grey Whales in Mexico

AP (Mar. 4, 2015) — Once nearly extinct, grey whales now migrate in their thousands to Mexico&apos;s Vizcaino reserve in Baja California, in search of warmer waters to mate and give birth. Tourists flock to the reserve to see the whales, measuring up to 49 feet long. (March 4) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins