What exactly is "gaping" anyway?

[herefishiefishie]

Hello everyone. Reading the responses to Alex's thread in a wide-open inhalant siphon brought somehing to mind...

When I first heard the term "gaping" in reference to ailing clams, I understood it to be that the shell was sagging open too wide, with the siphonal mantle drooping into the shell cavity. Clams that exhibit this symptom are in extremis indeed, and will likely die if something is not done immediately.

Recently I have read talk here about "gaping" referring to the inhalant siphon being open too wide for long periods of time. I have seen clams do this from time to time and return to "normal" appearance, apparently none the worse for wear.

So, what is your definition of a "gaping" clam? Also, does anyone have a definitive reference that mentions gaping and what exactly gaping might be?

Thanks for your help,

[Edited by herefishiefishie on 02-12-2001 at 10:02 PM]

[MtnDewMan]

"The most visible indication of the health of a tridacnid clam is the incurrent syphon. This slit-shaped opening should be closed most of the time. Normally, clams open it just for a short period of time. If the incurrent syphon is wide open or “gaping� (Sprung and Delbeek 1994), the clam is probably in a weakened state, caused most likely by the stress of shipping. This condition sometimes disappears after a few days, but the percentage of losses is quite high among these “gaping� clams, so they are best avoided."

http://www.animalnetwork.com/fish2/a...ll/default.asp

[herefishiefishie]

Excellent, thank you.

[I knew I was using the wrong terms (inhalant and exhalant) for the sihons. "Incurrent" and "excurrent" is what I should have been using. ]

[Evets]

I've always thought the term refered to the widened gap between the bottom of the shell halves (the hinge) that occurs after the byssal gland has been accidentally or purposefully removed. The widening of the gap causes the inhalant syphon to open wide, as describes in Delbeek/Sprung. I was just looking through Knop's book for his definition, but I have yet to find it. Thanks, MountainDewMan for the Delbeek/Sprung definition. I'm always happy when I learn something new.
-Steve