Green Eggs & Sand - Part IX

Later that evening, we all strap on our boots and waders, pile into several vans and head over to Kimball’s Beach – a narrow stretch of shoreline bordering Delaware Bay.  There, we are divided into three separate groups and are provided with some hands-on learning experiences by three Limulus experts.
            Jane Brockmann leads us in a mini-lesson on the spawning behavior of horseshoe crabs.  We watch as she pulls a most reluctant pair (who are heavy into amplexis) from the water to show us their undersides (and also their indignity).  Holding the joined crabs in both hands, Jane describes the various anatomical processes these crabs are undertaking.  It is quite obvious that her subjects are less than eager about this seaside “Show and Tell,” and are doing everything in their power to escape her clutches.  But, Jane is persistent and we are treated to a “hands-on” experience that is much more authentic, and certainly much more exciting, than any found in the pages of a stale textbook.
            We move to an area just off the beach where Heidi Hanlon of the New Jersey Fish and Wildlife Service gives us a lesson on horseshoe crab tagging procedures.  Heidi lectures on how tags are fastened.  She demonstrates using another very reluctant crab – one who is trying her best to wriggle out of Heidi’s hands (apparently horseshoe crabs are not natural exhibitionists – they have to be coxed into this new role).  Heidi shows how a small hole is drilled into the trailing edge of a crab’s shell and a tag with a “Christmas Tree” pin is quickly inserted into the hole.  Heidi uses a standard Black and Decker rechargeable drill with a specialized drill bit to demonstrate the procedure.  The drill bit is outfitted with a rubber stopper to avoid drilling through both sides of the carapace.
            Each horseshoe crab tag has a number to identify the crab as well as an address or telephone number which the “finder” can use to report vital data.  In some cases, people who report a tagged crab will receive information on the project as well as specific crab data.  A toll-free number is also inscribed on the tag.  The tags also provide scientists with valuable information relative to a crab’s migratory pattern over a period of several years, where and when it spawns, what side(s) of the Bay it tends to inhabit, the distances it travels from year to year, and population counts in order to determine any annual statistical fluctuations in numbers.  You may have a small notebook in the glove compartment of your car that keeps track of similar information during family driving ventures.
            Our third station features the “Grand Old Man of Horseshoe Crabs” – Carl Shuster.  Shuster is plopped into a beach chair as we gather around him in a semi-circle at the edge of the incoming tide.  He is in his element.  With a very large male in his hands he proceeds to tell us about the crab’s unique shell shape.  “For most of them you can draw an outline – a perfect circle,” he says.  “These creatures are architecturally strong – they can do all of their life functions – breathe, eat, spawn, locomotion…anything you can think of…can be done underneath the shell – completely protected.”
            We are a rapt and eager audience as Shuster continues, “Scientists seem to think that the ancestral type of horseshoe crabs is trilobites.  The trilobites superficially look a lot like horseshoe crabs.  However, Limulus, from DNA studies, goes back about 20-35 million years.  The Asiatic species are even younger.  In terms of reproduction Limulus has, what would appear to be, an advancement – a multitude of males.  All the Asiatic species have single male/female mating and if there are multiple males they are in tandem – like a railroad train and they have two pairs of claspers.  The first pair in the Asiatic crabs, instead of being strong like in the American species, are weaker, but the Asiatic species are the ones that grab the female crab first.  The second pair of claspers are bigger and stronger.”
            We are eager students, but no less eager than our instructor when he says, “To me that’s pretty fascinating stuff.  If there’s anything a creature can do this thing can do it.  The only thing it can’t do is back up.  It’s only option is to move forward.  It’s the only thing I’ve found that they really can’t do.  You have to realize that what you see today will never happen again.  That’s how complex this crazy thing is.  The environment is just as important as the animal.”
            Exhausted, tired, and worn out we head back to the campgrounds for a well-deserved good night’s sleep.