Sarah:
Happy to help out.
First, goodness there is no need to consider sacrificing any of these animals. As we explained in our original 2009 presentation, there is an easy way to get BC Floaters to resume and remain in a normal body posture.
The following internet link should pull up the original 2009 poster pdf file where we answer many of your questions.
file:///Users/edwardzalisko/Downloads/BC_Floater_SICB_2009_Poster-libre.pdf
If somehow that link does not work, select the following link to go to my Academia.edu website, where this and many of my research projects are described. In the next few weeks, I hope to add additional information to the Academia.edu website.
https://blackburn.academia.edu/EdwardZalisko
In short, it looks like the inverted animal (belly up) in the photos (leucistic?) may very well be a floater. Our animals typically have even more inflated lungs, that were often easily seen hyperinflated when looking through the body wall. But some show the trait less dramatically, and some float on their sides.
As we note in the 2009 poster, the most consistent way to help these animals remain in normal posture is to provide a downward current such as that generated by a trickle filter that hangs on the back of a tank. In addition, the BC Floaters should have a place to hang on when they are pushed to the bottom, so that they can stay down.
Research we presented in 2012 reveals that there is some sort of anatomical blockage of the respiratory passageway (likely the very short trachea) that allows them to inhale but not exhale. In the next two years, I expect to have an anatomical study completed documenting the problem. One of the world's experts on amphibian respiratory tracts has agreed to collaborate.
Other researchers working with axolotls have reported seeing something like the BC Floater trait. Your descriptions are most consistent with what we see in our colony. We have hundreds of BC Floaters in a colony supported by our undergraduate students working with me at our small college (Blackburn College).
I plan on presenting a large paper integrating the research completed to date once we can explain the mechanism that causes the floating. Right now, we are carefully studying the properties of the trait and conducting anatomical studies.
Axolotls may float for many reasons that are not the BC Floater phenotype. Most commonly, 1-2% may float as a result of "ingesting" air into the digestive tract. Disease can also result in various floating behaviors.
"Normal" axolotls supplement the oxygen they get from their gills by occasionally gulping air into their mouths. I often see my large adults of normal body phenotype do this. The animal then gradually sinks down, releasing the air from its mouth. So your note about this behavior reflects a common behavior.
By the way, we keep all of our BC Floaters in tanks with downward trickle filter currents and it is very rare to see the floating behavior return. A study we are about to present demonstrates that about half the animals that are floating, and then submerged for a day, will resume the floating behavior if returned to still water in an aquarium. So the downward flow seems to be a good situation to inhibit the resumption of the floating trait.
However, when we are raising a large cohort of axolotls, and assessing the onset and frequency of the phenotype, we raise them in still water in cups of various sizes. It is this still water condition where we will see the phenotype most likely expressed.
In a tank with a downward flow, I suggest a few more adjustments:
1) Position the filter on one side, so that the axolotl can select the most comfortable flow or current. In general, axolotls do not do best in high currents. Their native habitat is typically standing water (lakes in Mexico, that are variously disappearing).
2) Provide shelters within the tank, that may be clay pots (clean, new pots broken in half) or even a clean glass jar on its side, so that the axolotl can further escape currents, and
3) have nothing else but large rocks on the bottom. As you will see advised in many axolotl blogs, gravel on the bottom can be consumed by axolotls, potentially leading to some serious problems. We have worked through this problem in axolotls we had.
I hope the above helps and results in recovery. The BC Floater trait is an inherited trait. Thus, the behavior is a "phenotype" and the genetics the "genotype". Thus, BC Floaters can recover from the phenotype, but still retain the genetic potential to produce offspring with the trait.
Finally, as our animals grow larger, they seem to outgrow the trait. I think the larger body mass helps them tend towards the bottom. But we have had animals float, upside down, in still water, for more than a year! (The gills tend to grow longer, a type of acclimation, to the increased dependency on the gills for gas exchange).
Best,
Ed Zalisko, Ph.D.
Professor of Biology
Blackburn College
ezali@blackburn.edu
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that was my best guess on what the issue was. I have floaters, but they dont float upside down or on their side, and not for weeks at a time.. This made me think it was a genetic disposition. I just wanted some opinions
