[Taxacom] Sally Lightfoot crab piss photo

[Robin Leech]

Pardons.  I stand corrected.
Robin

-----Original Message-----
From: Geoffrey Read [mailto:gread at actrix.gen.nz] 
Sent: March-31-13 7:53 PM
To: Robin Leech
Cc: taxacom at mailman.nhm.ku.edu
Subject: RE: [Taxacom] Sally Lightfoot crab piss photo

Somewhat bemused Robin & Doug. It's very likely urine. Lots of crustaceans
secrete urine. This below is along the lines of what I was wondering - if
it's some sort of signalling behaviour, visual rather than chemical in the
Sally Lightfoot crab. Unless it lands on the opposing crab!

"... a confident lobster may use urine signals to influence the behavior of
its opponent into giving up the fight at an early stage. For both winners
and losers, urine release is linked to offensive behavior and increases as
the intensity of agonistic behavior increases."

Breithaupt & Atema (2000) The timing of chemical signaling with urine in
dominance fights of male lobsters (Homarus americanus). Behavioral Ecology
and Sociobiology.   Vol. 49, No. 1

Geoff


On Mon, April 1, 2013 1:21 pm, Robin Leech wrote:
> Geoff Read,
>
> I do not think that any arthropods have a urinary system that excretes.
>
> Robin
>
> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu
> [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Geoff Read
> Sent: March-31-13 6:07 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: [Taxacom] Sally Lightfoot crab piss photo
>
>
> This is intriguing. I'm curious if this behaviour is known.
>
> http://www.flickr.com/photos/psnz/8597352100/
>
> Remarkable photo. What initially struck me was it looks like one 
> stream comes from the center forehead, but this must be an illusion as 
> the stream is cut off or doesn't catch the light.  The detail is not 
> quite good enough to tell. This unrelated photo linked below seems to 
> show a pair of nozzles below the ventral edge of the rostrum, and they 
> might be forward-facing urinary openings?
>
> http://www.flickr.com/photos/ztjackson/3860806041/
>
> Geoff Read