Trophi structure in bdelloid rotifers

Bdelloids show a rather uniform morphology of jaws (trophi), named ramate. The most recognizable feature is the presence of a series of teeth forming unci plates. The unci are not uniform in size; each plate has 1-10 major median teeth. Using SEM pictures of trophi and data from the literature, we analyzed the number of major unci teeth in relation to trophi size, total number of teeth, and environmental features. Variability in the number of major unci teeth in bdelloids is not related to trophi size or to total number of unci teeth, while total number of unci teeth and trophi size seem to be related to each other: larger trophi in general have more teeth than smaller trophi. Few major teeth are more common in species living in water bodies where they possibly eat unicellular algae, while more major teeth are more common in species living outside water bodies, among mosses and lichens, where they possibly eat bacteria.