But, I ask you, why on earth would this clam be called a Horse -- be compared to such a large hoofed mammal?

I don't see a physical resemblance -- doesn't whinny like one -- doesn't eat hay. Could it be because of its size?

Indeed, as clams go, big they can be. They have been known to reach seven-eight inches in length -- weighing in at as much as three or four pounds!

Camano Island's Cama Beach State Park, the state's newest, is a habitat Gapers and a plethora of marine life seem to like a lot. Here in its generally quiet waters where gravel, mud, sand, and pieces of broken shell are mixed together is a place where, as you walk along its lower tide beach, mini fountains of water shoot upward several feet. For, yes, below the surface at the low-tide line, Tresus capax individuals sense an intruder -- they're moving into protection mode -- they're retracting their long siphons; and in so doing, creating upward spewing jets of water.

It's generally accepted that the length of a clam's neck or siphons and its overall size (with exceptions) indicate how far below the surface it habitates. Hence short siphoned and smaller Littleneck Clams, also found in abundance at Cama, live closer to the surface; while the huge low living Geoduck is a subtidal species with a neck extending upward some three feet.

When open, a Horse Clam can extend its big "foot", which is used for digging-motility. And when ready to close shop, it can then utilize a strong adductor muscle to close its big bivalves, which are held together at an interlocking hinge by strong cartilage.

Found on our beaches, or those from British Columbia to Baja California, the empty shells are generally puffy and oval to oblong appearing, chalky-white, overall rather smooth, although fine concentric lines can be discerned, and they often have a thin brown organic material called a periostracum covering the outer portion of the shell. (It has generally worn off -- peeled off -- the upper part of the shell.)

Holding a large empty hinged Horse -- opening facing me -- I was immediately struck with the notion that the gaping look reminded me of the mouth of a comedic character. Yes, the open mouth of a whimsical hand puppet or a Sesame Street original.

Are they edible? Yes. But some clammers find the species not as tasty as others, so it's not unusual during clamming season to find Horse Clams left behind on the beach.

And death will surely follow if left "high and dry" as they are unable to rebury themselves. Seems Gapers also need the pressure created by their sand and gravel surroundings to keep them intact -- help hold those two big valves together to protect their soft internal organs: heart, gills, gonads, stomach, and nerve nodules. Responsible diggers therefore will rebury them at the approximate depth they find them.

On closer scrutinization at the beach, I found the shells to be more fragile than they appear at first glance. So not surprisingly, clam digging often breaks the big Gaper shells; drying out the meat and rendering it unsuitable as eats -- a reason also why Gapers are not as often sought after by the commercial procurers. Some fisher-folk who choose not to dine on them retain and use their flesh as fish bait.

And interestingly, many of the Gapers carry several commensal passengers within their bivalves: a pair of soft-bodied Pea Crabs, Pinnixa faba -- conveniently and practically, a male and a larger female. Measuring some ½ inch across the carapace, the Gaper residence affords them protection, and ocean waters delivered by the clam's long siphons provide them with food. A great arrangement for the Pea Crab and of no harm, it is felt, to the clam.

Please contact At the Beach Now if you have information as to why, or wish to offer a reason as to why you feel the non herbivorous, non mammal, Tresus capax, Gapers, are called Horse Clams. We'll report back on the survey's findings.