[Taxacom] Sally Lightfoot crab piss photo

[Geoff Read]

Ah ha. It's apparently a last resort in anti-predator defensive behavior,
according to one who has experienced it (* "... when cornered, they can
urinate extremely accurately to a range of two feet; they seem to aim for
the eyes.").  How dastardly of them. And less interesting. Still -
whatever it takes to survive out there must be legit ...

* An observation somewhat parenthetically appearing here:
http://sites.lafayette.edu/hollidac/research/osmoregulation/atpase-assay/

Geoff

On Mon, April 1, 2013 4:25 pm, Robin Leech wrote:
> 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/