Moderators: Chris S., Pau, Beatsy, rjlittlefield, ChrisR
Hi Bruce and thanks.Bruce Taylor wrote:Hi Carlos. Gorgeous! The phase contrast really shows the ventral cilia. In this video, the two "spineless" specimens are a bit smaller than the others. It is hard to be sure, without spending a bit of time with the population in culture, but this could be simply a developmental difference. The ones without tails might be proters from a recent division.
The "tails" of chilodonellids are usually regarded as normal species-defining characters. A while ago, you showed me an interesting chilodonellid with a large secondary spine on its dorsal surface, and I speculated that it might be a defensive adaption, like the dorsal spine of "Aspidisca turrita" (a defensive form of A. lynceus). To my knowledge, defensive phenotypic changes (common in euplotids) have not been recorded in chilodonellids, so it would be something new and interesting. However, these posterior tails are found in ordinary populations of several species of Chilodenella and Pseudochilodonopsis. I suspect that their purpose (if they have a purpose...not all structures do!) is more likely to be thigmotactic (i.e. allowing the organism to orient itself by "touch") than defensive.
) Hi Bruce.Bruce Taylor wrote:Well, small specimens with tails could be the opisthe (rear half) of a recent division. In any case, I suspect that we're looking at normal variation within this population, rather than a predator-induced defense (unless you start seeing lots of those guys with the big dorsal spines!
If you want to pursue it further, you could start by gathering morphometric data, to determine the normal size range and the prevalence of "tails." If you can keep the population alive, you could try maintaining one culture in company with predator species, and a second culture without predators.
