Phylogenetic reconstruction of metazoan α-CAs with a focus on molluscan sequences. The phylogeny was reconstructed using PhyML and Bayesian inference methods, the topology presented is that resulting from the Bayesian method (see Additional file 4: Figure S3 for the PhyML topology). Node support values indicate aLRT values, and Bayesian posterior probabilities expressed as a percentage respectively. Only values above 50 are indicated. Sequence data was derived from 2 vertebrate species (Homo sapiens and Mus musculus, in black); 1 cephalochordate (Branchiostoma floridae, in grey); 6 bivalve molluscs (Crassostrea gigas, Crassostrea nippona, Patinopecten yessoensis, Pinctada fucata, Pinctada margaritifera and Pinctada maxima, in blue); 4 gastropod molluscs (Haliotis gigantea, Haliotis tuberculata, Lottia gigantea, Turbo marmoratus, in blue); 2 sponges (Amphimedon queenslandica and Astrosclera willeyana, in orange); and 3 unicellular organisms (Nostoc sp., Chlamydomonas reinhardtii and Neisseria gonorrhoeae, in black). The α-CAs involved in biocalcification are in bold/underlined. Nacreins and nacrein-likes are indicated by a red star. Well supported aLRT/bootstrap values (>90) are indicated by a green point due to lack of space. CARPs: Carbonic Anhydrase Related-Proteins.