[Taxacom] Sally Lightfoot crab piss photo

[Geoffrey Read]

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