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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 >>>>