I have a question or two: Do the zoox reproduce along with the corals, in a perpetual symbiosis?
Yes. Zoox become "senescent" and are eliminated (I think it is probably actually viral lysis, but anyway..) and those in the tissue divide by mitosis according to host nutrient limitation or seawater nutrient
There's a bit of a chicken and egg situation, I assume, but presumably at some point the coral existed first, then the zoox arrived. Similarly, what happens when a bleached coral seems to regain it's zoox (perhaps there are always a few that remain to regenerate)?
Yup. Most recovery seems to happen from remaining populations although they can acquire them from the water column (but not to the degree that a pale coral becomes brown again). Bleaching is a gradient or spectrum - the extreme ened of noramlly dynamic population fluxes, and I have never heard of a case where a bleaching event resulted in the loss of all zooxanthellae.
Can they migrate in the current or do they generate a spore like state as anaerobic bacteria do to survive in oxygenated conditions when necessary?
They are flagellated and motile in the water column, and lose the flagellum when taken into coral tissue, but regrow the flagellum if re-released back in the water from the tissue
If they do sometimes migrate, are there ever cases when differently colored, but otherwise identical colonies mix colors? I've never heard of it, but wonder what mechanism would either facilitate it or prevent it.
Zoox are golden to deep brown, and color patterns in corals would not really be explained well by hosting multiple types, but this does happen and is the normal state for many corals.
Yes. Zoox become "senescent" and are eliminated (I think it is probably actually viral lysis, but anyway..) and those in the tissue divide by mitosis according to host nutrient limitation or seawater nutrient
There's a bit of a chicken and egg situation, I assume, but presumably at some point the coral existed first, then the zoox arrived. Similarly, what happens when a bleached coral seems to regain it's zoox (perhaps there are always a few that remain to regenerate)?
Yup. Most recovery seems to happen from remaining populations although they can acquire them from the water column (but not to the degree that a pale coral becomes brown again). Bleaching is a gradient or spectrum - the extreme ened of noramlly dynamic population fluxes, and I have never heard of a case where a bleaching event resulted in the loss of all zooxanthellae.
Can they migrate in the current or do they generate a spore like state as anaerobic bacteria do to survive in oxygenated conditions when necessary?
They are flagellated and motile in the water column, and lose the flagellum when taken into coral tissue, but regrow the flagellum if re-released back in the water from the tissue
If they do sometimes migrate, are there ever cases when differently colored, but otherwise identical colonies mix colors? I've never heard of it, but wonder what mechanism would either facilitate it or prevent it.
Zoox are golden to deep brown, and color patterns in corals would not really be explained well by hosting multiple types, but this does happen and is the normal state for many corals.
