Protists represent the largest proportion of eukaryotic taxa that dominate (in terms of numbers and diversity of species) freshwater and marine environments. These aquatic protists include; the free-living kinetoplastids, which are sometimes outshined by their parasitic-sisters, the trypanosomatids and Leishmanias.Parasitic taxa that are capable of changing morphologies or cellular differentiation do so in various ways. Such changes may be dependent upon a shift in the host internal environments, resulting in repurposing appendages or proteins through RNA editing mechanisms which allow the parasite to change morphologies through various life-cycle stages; or by moonlighting proteins, whereby proteins characterized by their primary functions can also have a hidden secondary function (which can relate to the virulence of parasitic taxa) Trichomonas vaginalis (Trichomonadidae), Salpingoeca rosetta (Salpingoecidae), and Naegleria gruberi (Vahlkampfiidae) are well documented protists (amongst others) that have been observed to change morphologies. These species are largely removed from the kinetoplastids (Discoba) and each other, Metamonada, Opisthokonta, and Percolozoa respectively, yet display the same capabilities for morphological change, albeit under differing conditions. This display of function would suggest that this mechanism (either for parasitic virulence or as a ‘fight-or-flight’ response to changes in the environment) is likely to have evolved from a common ancestor linking all four lineages and not evolved independently after divergence.