Dolphins we saw every morning, pods ambling their way south. I even glimpsed the fin of a small shark or ray in the swash of a breaking wave. No pelicans, though, no trifecta. The vague disappointment was kind of like being a kid at Christmas…presents a plenty including some you really wanted, but no Red Rider BB gun with the adjustable sights and patented lever-action loading. Just as often, though, you got something so unexpected that it made all the other stuff, actual or not, seem trivial. My unexpected present this summer was five different species of crab (OK; four, since one is technically more closely related to spiders and scorpions).
First up, while walking the beach and dodging waves in the late afternoon, I discovered (quite literally) an old childhood acquaintance, the mole crab. Bethany has been busy with beach replenishment in recent years so mole crabs haven’t been as abundant as at Assateague Island or other wild beaches. Mole crabs belie the old saying, “crabs walk sideways and lobsters walk straight”. In this case, they walk straight backwards. Mole crabs dig themselves into the upper beach almost to the limit of wave washed wet sand and sit just below the surface waiting for the next wave. As the wave washes over, they thrust out their feathery antennae and use them like tiny nets to filter out bits of debris and plankton. They draw their antennae through the mouthparts and pick out the tasty bits. The one I grabbed was a fat female, the size of my thumb (males are much smaller), scuttling on the wet sand in the backwash of a wave. I took her picture and watched her dig in and vanish as if by magic before the next wave.
As the shadows lengthened and the air began to cool from the blistering heat of the day, we repaired to the boardwalk for our evening constitutional. No visit to Bethany is complete without a lap of the boardwalk, all 5/8 of a mile of it. Near the north end, a flicker of movement caught my eye. There, in the shadow of a piling was a hole about the size of an old-fashioned half-dollar. Next to it, standing guard, was a ghost crab, again, the first I has seen on Bethany in some time. Ghost crabs are sand-colored with eyes on stalks like tiny periscopes, and run wicked fast. A mature female (big females take the beach farthest from the waves—location, location, location), she was nervously pacing back and forth by her burrow (which may be up to 3 feet deep), waiting for the gloom to deepen enough for her to set out for the beach and begin her night’s foraging—hunting mole crabs, beach fleas, and general scavenging. Now that I knew what to look for, I saw the entrances to several other burrows, some with tell-tale sand fans at the entrances indicating recent excavation. Keeping to the shadows, this one dashed a zigzag course through the compass grass, over the artificial dune, and quickly vanished from sight.
Next morning’s stroll along the beach revealed another temporary gift, a horseshoe crab. Dubbed “Delaware’s dinosaur”, it actually predates those mighty beasts by over 100 million years—truly a creature from another world. Every spring, horseshoe crabs come ashore to spawn just as they have since the mid-Permian, a third of a billion years ago. Back then, there was almost no life on land—just a few struggling primitive plants, so laying your eggs at the edge of the water was the safest thing you could do. Nobody told the horseshoe crab that things have changed in the interim—animals have evolved to live on land, including, several species of shorebirds who time their spring migrations to coincide with the spawning cycle.
Everything about this animal screams different—their blood is copper, not iron based. Horseshoe crabs’ ancient lineage predates that of crustaceans; technically, they are more closely related to trilobites and scorpions than to true crabs. Although their Latin name, Polyphemus refers to the Cyclops in the Iliad, horseshoe crabs actually have ten identifiable eyes, plus light sensitive sections on the upper and lower shell and on the tail. No problem with chewing gum and walking here—the crabs’ mouths are between their front legs, so in order to chew food, they must be walking. They swim upside down, righting themselves with the long dangerous-looking tail spine called a telson. Once on the bottom, the hydrodynamic curves of the upper shell keep them pressed to the sand—a good thing if you live anywhere near the surf zone. This one was a big female, 30 years old at least, cast up by the waves and hunkered down to wait the turn of the tide. I tossed her back into the sea with a whispered bon chance.
The beach was getting hotter and we were in desperate need of lunch. We retreated back to the house where, groggy from food and the heat, we began reading our new books in the chill of the AC. I can’t sit still for more than a few minutes so I took a walk to the local boat ramp to see what was going on. The tide in the back bay was at slack low, exposing the mud banks lining the channel. Salt marsh hay waved in the sultry breeze and laughing gulls and terns wheeled overhead. Salt marsh dragonlets, a small dragonfly and one of the few insects that can breed in salt water, hawked mosquitoes over the mud. Movement on the bank caught my eye, fiddler crabs feeding on tasty bits embedded in the mud. Females were using both small claws to shovel in the gooey mud, looking like small boys at a county fair pie-eating contest.
The slightly larger males were using their single small claw to feed, occasionally looking around and waving their huge “fiddle” claw to attract females. The motion the males use to attract females is familiar; the universal “come on over” wave. Males also use their large claw to wrestle with other males over a comely she-crab. Some males are “right clawed” others “left clawed”. I wonder what the ratio is and how they fare in combat. When I took fencing, I hated to go up against a lefty. Southpaws (or, to be more accurate, southclaws) have the advantage in an otherwise fair match—they are used to fighting the far more numerous righties and right-handed fencers are unaccustomed to fighting a mirror image of themselves. I doubt it’s so simple for fiddlers--my best guess is that the genetics will see-saw with whoever is in the ascendancy, giving the advantage to the other side in a few generations.
The tide was starting to come in, blue crabs and the occasional rockfish swam past looking for stragglers. The fiddlers were going down their burrows and pulling a plug of mud in behind them to wait out the rising water and its predators coming in from the deep. Nap time for me and the fiddlers (another gift of the beach).
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