Diario de bogsnail

A little over a year ago, I found what appeared to be a butter clam shell, but with three distinct scars that seemed to be built into the shell, an atypical growth pattern I had never seen before, and since, haven't seen in person. I have not been able to find any documentation of this deformity online, nor any research. Taking matters into my own hands to give this deformity a simpler name, I've decided to call it Butter Clam Clefting. More recently, I came across an observation by ecologyquail on this very site that caught my eye: a butter clam, with four clefts much like the one I had found a year prior, in nearly the same location as i had found my specimen. Easily within a few thousand feet. I began to speculate why this deformity would have arisen, perhaps due to the local environment, which would explain why two specimens had been found in such close proximity; perhaps conditions in that local area had impacted the clam as its shell grew.
Since then, I have scrolled through every last observation of Butter Clams on iNaturalist, and found four more instances of clefting in Butter Clams. One had four clefts, the three others with just one. But in all these cases, the deformity was rather consistent.
One or more deep, scar-like "clefts" in the outer layers of the shell, running from the ventral margin upwards, but never reaching or closely approaching the umbo, and (with what limited instances seen) do not tend to occur more or less on either valve, nor anterior or posterior.
All observations on iNaturalist of this phenomenon are located in the Puget Sound. This may be due to higher concentration of the species in the area, higher concentration of beachcombers or shoreline, or, more interestingly, the deformity occurring more in this region than out. If the third is the case, than that could point to it being an environmental factor like temperature, or pollution, due to the Puget Sound's higher temps and urban exposure to irritative and toxic pollutants. In any case, the cause may only take effect later in the animal's life, indicated by the lack of clefting near the umbo, or perhaps they had been there and had since eroded away, but I find this unlikely due to the abruptness of the beginning of the cleft.

In any case, this deformity deserves more intrigue, and I'm very curious about its cause, and any effects it may have on a live animal.

Bogsnail, 11/14/23