[NatureNS] Horseshoe crabs here in Nova Scotia?

From: "Elizabeth Doull" <edoull@ns.sympatico.ca>
To: <naturens@chebucto.ns.ca>
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Date: Thu, 14 Feb 2008 14:10:03 -0400
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I recall seeing some horseshoe crabs here in Nova Scotia when I was a kid. 
I haven't seen one for years so are they extinct or not in this province?

Thanks   Liz
----- Original Message ----- 
From: "Roland McCormick" <roland.mccormick@ns.sympatico.ca>
To: <naturens@chebucto.ns.ca>
Sent: Thursday, February 14, 2008 1:41 PM
Subject: Re: [NatureNS] Why save the Red Knot? - vertebrate hegemony?


>I read in the paper recently that one of the boys I taught in school was 
>fined a couple of thousand dollars for using crabs as bait to catch 
>lobster. I wondered about that at the time because I had never heard about 
>using them for bait before, or the reason for the fine.  I assume that is 
>what we are talking about here, and that there is a good reason for it.  I 
>can assure you that if this is true the fines are a good deal more than 
>$25.
>
> Roland.
> ----- Original Message ----- 
> From: "Paul S. Boyer" <psboyer@eastlink.ca>
> To: <naturens@chebucto.ns.ca>
> Sent: Thursday, February 14, 2008 11:26 AM
> Subject: Re: [NatureNS] Why save the Red Knot? - vertebrate hegemony?
>
>
>> The horseshoe crab is a living fossil, virtually unchanged since the 
>> Jurassic Period (in the middle of the Age of Reptiles).  Tracks of 
>> spawning horseshoe crabs have been found in Devonian rocks of 
>> Pennsylvania, which are far, far older.  Fossil relatives are found  in 
>> Manitoba from the Ordovician Period, about 445 MY old.
>>
>> There are only a few species of horseshoe crabs in the world (the 
>> American one, the subject of the program, and three minor Asian 
>> species). The American horseshoe crab is the largest and the most 
>> numerous, and the most spectacular to watch. New Jersey is the center 
>> for their abundance and average size, or at least it used to be.
>>
>> It is not the medical use that threatens the population, but the 
>> wasteful and (IMHO) lunatic use of horseshoe crabs as bait, or even 
>> fertilizer.  I have not checked recently, but when last I looked an 
>> annual license to take unlimited numbers of horseshoe crabs (seized  from 
>> the beaches while they are trying to spawn) was a mere $25.   Horseshoe 
>> crabs have a long lifespan, and do not recover quickly from  the 
>> depredation of being hauled away in truckloads.  Actually, the  Red Knot 
>> probably can increase its numbers faster with environmental  change than 
>> can the horseshoe crab, because the generation time is  shorter for the 
>> Knots.
>>
>> On 14 Feb 2008, at 2:04 AM, Stephen Shaw wrote:
>>
>>> Unfortunately missed the program, but I had a mild comment on the 
>>> species-ist
>>> emphasis here (sent it earlier but it didn't do through).
>>>
>>> Nothing against the Red Knot and of course I hope it survives, but  the 
>>> received
>>> vertebratocentric perspective on this is interesting.  As the blurb 
>>> below
>>> states,
>>> there are lots of other similar peep species around, but the  horseshoe 
>>> "crab"
>>> Limulus polyphemus is a unique species here and has been  practically 
>>> wiped out
>>> in many of its former habitats on the US East coast, according to  Bob 
>>> Barlow, a
>>> former student of Hartline (see below) who still works on it,  latterly 
>>> on its
>>> visual behaviour under water. Apparently the market for its blood  is 
>>> the main
>>> reason for the punitive "harvesting".
>>>
>>>  Besides having a far more interesting, ancient lineage, Limulus has
>>> contributed to several outstanding scientific discoveries in vision 
>>> science,
>>> notably that of "lateral inhibition" by which the nervous system 
>>> sharpens up
>>> percepts, enhancing edge-detection in images.  This has emerged as a
>>> common enhancing operation elsewhere in nervous systems, but  originally 
>>> came
>>> mainly out of work on the compound eyes of Limulus in the 40s-60s  --  
>>> netting a
>>> Nobel prize for H.K. Hartline, of the then Rockefeller Inst (now  Univ). 
>>> In the
>>> 60s, S. Yeandle made the first recordings of single photon captures  in 
>>> the same
>>> eye (since then recorded in vertebrates, though not in Red Knots), 
>>> while in the
>>> 70's, the first detailed analyses of how photoreceptor currents work
>>> (semi-universal) came out of measurements on huge photoreceptor  cells 
>>> in the
>>> ventral nerve that had been thought before this to be an olfactory 
>>> structure
>>> (analysed since in vertebrates, though not in Red Knots).   Circadian 
>>> rhythm
>>> mechanisms are big news at present (molecular mechanisms), and one  of 
>>> the best
>>> analyses of the circadian control of an eye by the brain came from 
>>> Barlow and
>>> colleague's work on the Limulus lateral eyes.  There are at least  two 
>>> other
>>> sets of eyes in horseshoe crabs, one UV sensitive and one in the 
>>> telson...
>>>
>>> None of these conceptual advances were minor cul-de-sacs and all  have 
>>> become
>>> incorporated into the neuroscience base, ever expanding. Limulus 
>>> deserves great
>>> respect as a unique and unusual pioneer invertebrate animal that  ought 
>>> to
>>> survive.  What has the Red Knot done to gain comparable respect?
>>>
>>> So, if I had to curry up votes for one of the two endangered  species, 
>>> it would
>>> be for the unique and illustrious horseshoe crab, first.  "Why save  the 
>>> Red
>>> Knot?" indeed -- do it second.
>>> Steve
>>> ******************************************
>>>
>>>
>>> Quoting Elizabeth Doull <edoull@ns.sympatico.ca>:
>>>> Why save the Red Knot?
>>>> PBS
>>>> flocks of shorebirds, the red knot is fairly average looking. In  fact, 
>>>> only the most practiced bird watchers may be able to  distinguish this 
>>>> medium-sized, plump peep from the thousands of  other shorebirds 
>>>> playing tag with the waves. Yet, somehow the red  knot has caught the 
>>>>