Ten Thousand Friends - Part II

As we strolled up the beach we watched transfixed as couples mated on every stretch of sandy real estate they could find.  Almost alien in appearance, these sub-marine “tanks” plowed their way out of the water, up the beach, and into each other with all the delicacy of a frenzied herd of bull elephants drunk on fermented fruits.  There were the usual twosomes and threesomes, and occasionally we would come across a foursome, a fivesome, and even one over-stimulated sixsome – a coupling which, I am sure, would have put most adult film stars to shame.  Cameras clicked and notes were scribbled as we traipsed through rippling waves to watch these critters perform – each of them totally oblivious to our presence and each totally absorbed in a ritual propelled by tides and temperatures and hormones…forces as old as time itself.

Occasionally Glenn would pause and proffer some instruction on the biology, anatomy, or physiology of these ancient critters.  At one juncture he gathered up a lonely male – turning it over to reveal selected features of its anatomy.  He pointed to the underside and identified each of the six paired appendages.  He told us how the horseshoe uses the first pair (the chelicerae) for placing food (they particularly favor marine worms and small clams) in its mouth.  The next pair of appendages are the pedipalps which are the first ambulatory legs.  In the adult male, the tarsus (final segment) of these legs are modified as a grasping appendage, allowing males to clasp the female during spawning – a unique coupling that will require considerably more attention later in this book. The “last” legs are the “pusher legs” which are used for both terrestrial and underwater locomotion.

Glenn swept his hand toward the tail and the five branchial "legs" – often referred to as book gills.  He told us how the horseshoe uses these both for propulsion (when swimming) as well as for "breathing."  Similar to the gills in a fish, they are a membrane that allows oxygen to pass through while keeping the water out.  We posed a few questions (“What’s the shell made of?”, “How long do they live?”, and “What is THAT thing?”) and our brief biology lesson was over.  Ever so gently, Glenn placed the uncomplaining “specimen” back on the beach right side up.  The over-hormoned crab lost no time in scuttling off to seek a ready female – completely oblivious to the gaggle of humans observing his departure.

Next Post - Part III