Most sources agree on the existence of 72 species within the Acanthuridae family but the number of genera ranges from 6 to 9, depending on the source. Acanthurids, commonly known as surgeonfishes, are characterized by the existence of the “   scalpel ,” a distinctive spine or group of spines on either side of the tail base, hence the common name surgeonfish. Color marks often emphasize the   scalpels and they are important for interspecies communication, as discussed in Communication below.