Phylogenetic relationship of Lepeophtheirus salmonis AChE1a and AChE1b with other acetylcholinesterases from Insecta, Nematoda, Arachnidae and Veterbrata is shown. The phylogenetic tree was constructed using a MUSCLE alignment at the Phylogeney.fr platform (http://www.phylogeny.fr/version2_cgi/index.cgi). The clustering of the AChE1 and AChE2-type of enzymes are indicated by boxes. The AChE1a and AChE1b of L. salmonis are also boxed. Branch support values are given in %. AChE1a and AChE1b were clustered with other AChE1 proteins and were clearly separated from AChE2 proteins in the phylogenetic tree.