[Delphinus]

I agree, there are places in the water column that are subject to some pretty wild temp fluctuations. I would imagine that the rate of change in those areas may not be insignificant in terms of what lives there and what tolerates it. It seems to me a tidal pool will warm up slowly as the day goes on, and then cool very quickly once the tide rolls in again.

I don't know if it was me who said "100% emphatically" that it was not disease but that it was heat, but I think I had tried to suggest that heat was a possible cause. Darren's clam exhibited similar behaviour as mine did. Mine started showing the bysal-gland-through-the-inhalant-siphon phenomenon immediately following the day I once forgot to turn my hood fans back on after I had disconnected them for some work I was doing. But in my case the temp only reached 94F. So let me state for the record "I'm not really sure at all" but I think that heat may have played a role in at least mine. But who knows, maybe it was going to do that anyways and it's just pure coincidence that it happened after the warm day. I have nothing to go on except the good word of the vendor that it was a different source as the infamous clams of last year (Pohnpeii clams I had heard) but then again that is not to say that it wasn't some other pathogen either (I'm sure there are plenty that spell trouble). I do agree that pathogens are a problem with clams more so than other things. Like for example how a chain reaction seems to happen when one dies all the others seem to follow suit (sometimes).

I had searched for any kind of info for the byssal gland sticking out of the inhalant siphon and I came up completely empty. Nobody offered any hints so all I had to go with was whatever I came up with. The only thing that was out of character was the heat spike.

It could just be I bought a weak clam ... who knows. Unlucky in clams. Ultimately I've got not a lot to work with other than guesses.