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Date: Fri, 11 Dec 1998 11:33:42 -0800 (PST)
From: <[log in to unmask]>
To: Ross Mayhew <[log in to unmask]>
Subject: Re: Bivalve defences (other than running away, hiding,              and being difficult to open, ie!!)
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Hi Ross,
 
Chama in southern California are often so heavily encrusted with sponges
(containing spicules) and bryozoans (with spines and avicularia) that
stars walk right over them thinking it's just another chunk of the reef.
It's a defense in that they avoid being detected--not in response to
attack.
 
Bivalves, as I'm sure you konw, sequester neurotoxins from their
planktonic prey in fatty tissues, usually magnifying the dosage to
something harmful to large predators, but this is usually done to avoid
poisoning the bivlalve itself, not as some defensive scheme, although the
net result might be predator avoidance after a few boughts with neurotoxin
poisoning...
 
> sounds right!!  NOW, could someone come up with some interesting ways
> bivalves actually defend themselves- do some have toxins?   Spicules?
> comensal relationships with unpalatable critters??  I would be quite
> interested to know!!
 
Probably not a commensalism--the benefit would go to the oyster, and the
other species would have to receive no benefit (+0) relationship; however,
since space is so often limiting, the valve probably is a benefit to the
unpalatable critter since it's a place to attach (important for sessile
spp.).
 
Cheers and pass along interesting responses,
Steve
 
Steve Lonhart
Department of Biology           Office:  (831) 459-4026
University of California        FAX:     (831) 459-4882
Santa Cruz, CA  95064           email:   [log in to unmask]
 
WEBSITE:  http://www-biology.ucsc.edu/people/potts/lonhart/