Ron's Musings

The Diodogorgia feeding experiment ”saga” continues.   Yesterday, I did the first two sets of supplemental experimental feeding observations.  I made about 90 movies watching polyps under both 16 cm/sec and 24 cm/sec laminar flow currents.   I did about 45 movies under each speed, and I hope that they show some good captures or attempts, and such.  I think they did, but it is really hard to tell by watching on the view screen of my little camera as I am taking the pictures.

Today, I will be duplicating the effort, but I will use turbulent flows.  Getting all of these data is great, but of course, it does – in one sense – slow me down, as I have to process and analyze all the movies.  That involves adjusting the brightness and contrast, if I can, to make viewing easier.  Also, I label the movies and such, so that I won’t make mistakes about what I am watching.  With over 500 movies, it is easy for my feak and weeble mind to get confused on occasion.  And then I have to analyze them for actual content.  Gonna take a while!!!

Still and all, even though this sets me back a bit on my schedule, it really is of no consequence – because the schedule is all of my own making.  I want to have the best project I can have, given some reasonable constraints of cost, time, and effort, and these new movies certainly help correct some early errors.   I took the original movies under these conditions as the first ones for this aspect of the project, and I really didn’t know how many I needed nor under orientations were best.   After looking at movies from all the other speeds, I have  a really honed appreciation of what I need.  I just hope that these will fit the bill.  

Doing this aspect of the project was an interesting process.  Initially, I had no intention of working on the question of exactly how do the animals captured their food.  The primary question was simply, “Was there a difference in the rate of capture between animals in laminar flow and turbulent flow situations?”  Additionally, I thought it would be interesting to see if the differences, if any, changed as the velocity of the current changed, so there was the additional question, “Was there a difference in the prey capture rates between animals in laminar and turbulent flows at different current velocities?”  These were questions driven by animal husbandry concerns; primarily, “What does a marine aquarist have to do to maintain these or similar animals in good conditions in an aquarium?”

In the process of doing those experiments, I thought it would be useful to have some movies of Diodogorgia polyps capturing Artemia, simply as visual aids for presentations.   However, once I had a couple of good movies of prey capture, the REAL question became evident:  Just How DO Diodogorgia polyps capture prey?  Frankly, the question actually has a much larger significance, because when I was reading references about gorgonian feeding, it became evident that the process was really a “black box” phenomenon. 

People have done experiments – a very few – about feeding in gorgonians, and have found feeding rates for some species, but there is no general model of how the polyps actually work to catch prey.  There are some data and ideas for other octocorals, primarily the lumpy leather corals, such as Sinularia and Alcyonium, but nothing for gorgonians such as Diodogorgia, where the polyps have to be projected up into the currents.  In most of the previous experiments, it simply is assumed that the polyps work to capture food, no thought seems to be given to the processes involved. 

And, if you think of it, prey capturing in such a small animal under the normal conditions it encounters has to be an amazing process.  The animal has to encounter the prey item, assess it, and capture it all the while in a strong (relative to the size of the polyp) current.   If you consider the dimensions of a small – tiny even - gorgonian polyp, and how long it takes a food particle (a tasty zooplankter, or a yummy particle of bacterial goo) to pass through the space around the polyp, all of the decisions about the food capture have to be made in small factions of a second.  All by an animal with no brain and, at best, a rudimentary nervous system.

This is really neat stuff, I think.  

When I get all done, I hope I have done a good enough job at this project that the people who review and read my work, think it is a neat project as well.

Until sometime later,

Cheers,