next message in archive
next message in thread
previous message in archive
previous message in thread
Index of Subjects
Index of Subjects 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 attention >>> of people around the world. >>> >>> The knot's dependence on the eggs of the heavily harvested horseshoe >>> crab has placed it at odds with another species -- humans. Conservation >>> groups, lawmakers, fishermen, scientists, and ordinary citizens have >>> all entered the debate. But even as our actions have imperiled the red >>> knot, we can also preserve the species, by regulating the fishing >>> industry and keeping clear of the beaches that the knots rely on during >>> migration. Where nature ranks in our system of values will dictate how >>> far we are willing to go to protect the red knot. >>> >>> There are millions of shorebirds in the world. Why all the clamor over >>> the red knot? How co