Figure 1

Schematic phylogeny of animals based on the report by Dunn et al[48] which, however, did not include the phylum Loricifera [1] (highlighted in red). It was placed here (dotted line) as branching with Priapulida and Kinorhyncha as reported elsewhere [49, 50]. Higher taxon designations are those used in references [48–50]. The Cycloneuralia, where Loricifera belong, are currently grouped within the Ecdysozoa, which also includes nematodes and insects. To the right of the phylogeny, several species are listed whose facultatively anaerobic mitochondria have been studied [10–14]; in no way does this imply the absence of anaerobic mitochondira in other groups. No biochemical data are yet available for the Loriciferan mitochondria [1].