Skip to content. | Skip to navigation

Personal tools
Log in
Sections
You are here: Home Blog Females should watch their weight

Females should watch their weight

By Leonard Ho - Posted Jun 24, 2011 06:00 AM
Now that I've gotten your attention, allow me to explain! When it comes to cleaner wrasses, males do not treat all females in their harem equally. Scientists have discovered male cleaner wrasses will tailor punishment for females according to the stakes ... and to her size.
Females should watch their weight

This beautiful photo of a cleaner wrasse in action was taken by Doug Anderson (Creative Commons)

Let's begin with a little background about cleaner wrasses (Labroides dimidiatus).  Cleaner wrasses are protogynous hermaphrodites, meaning they all start their lives as females.  The dominant female will change into a male and ultimately rule a harem.

Marine aquarists are familiar with cleaner wrasses' penchant for cleaning other fish by eating the ectoparasites off of their client.  But every so often, a wrasse will get greedy and take a bite out of the protective mucus membrane of their client, which results in the unhappy client making a quick retreat and leaving the cleaner wrasses without a food source.  Males are known to punish females after these events (in essence, blaming the females for his lost meal).  But does he punish all the females equally?

To find out, scientists exposed multiple pairs of cleaner wrasses to two types of foods: a preferred "prawn" food and a less-preferred "flake" food.  The scientists then removed the foods to see how the male wrasses punished the female he was paired up with.  They discovered:

  • Male wrasses would punish females more severely for "driving away" preferred foods compared to less desirable (less nutritious) foods.  The tastier the meal lost, the more punishment the males dished out.
  • Furthermore, male wrasses would punish large females more severely.  The reason for this behavior is simple: Large females are viewed as more of a threat to change sexes and become reproductive competitors.

In the wild, cleaner wrasses will form harems of one male with up to two dozen females.  The male will spend most of its time with the largest female ... not because he loves her most, but rather because he wants to monitor and control this female in order to prevent her from becoming a him.  And this recent study shows that the largest female also gets the worst of his punishments, even if she's not guilty of anything.

The practical lesson?  Aquarists interested in maintaining harems of fish - whether it be Fairy Wrasses or Anthias - may consider smaller females to reduce male-to-female harassment.

I apologize for the title!  I'll be sleeping on the couch tonight.


REFERENCE: The Proceedings of the Royal Society, Biological Sciences.

Author: Leonard Ho
Location: Southern California

I'm a passionate aquarist of over 30 years, a coral reef lover, and the blog editor for Advanced Aquarist. While aquarium gadgets interest me, it's really livestock (especially fish), artistry of aquariums, and "method behind the madness" processes that captivate my attention.

Website: http://www.advancedaquarist.com.

Document Actions
Filed under: ,
blog comments powered by Disqus

blog_sm.jpg

Contribute to our blogs!


Do you have news or discussion topics you want to see blogged?  Let us know!

 

ADVANCED AQUARIST