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An identification technique of commercially important cephalopods based on 16s RNA analysis was developed. A set of primers was designed to amplify a fragment of approximately 200 bp that presents enough variability for reliable species identification. Sequences from this fragment of 9 different authentic species were studied, genetic distances were measured, and a phylogenetic tree was constructed, with individuals of the same species grouped within the same cluster. Eight different types of commercial seafood products, mainly labelled as "squid rings", were analyzed and sequences were employed for species identification showing that FINS is a suitable technique for identification of processed cephalopods.

Identification of flatfish species using a DNA-based methodology was studied. The polymerase chain reaction was employed to obtain a 464 bp amplicon from mitochondrial cytochrome b gene. The sequences from this fragment belonging to 24 species were analyzed using a genetic distance method, and polymorphic sites were determined. The fragment was found to be highly polymorphic (231 sites), and this permitted the differentiation of most of the species. Phylogenetic tree construction was employed to allow the identification of flatfish species. As a result, each species was grouped in a well-differentiated clade, except for two pairs: Limanda ferruginea and L. limanda, and Solea impar and S. lascaris, which could not be differentiated. On the basis of the sequences obtained, restriction enzymes were selected to provide specific restriction profiles, which allow the differentiation of 21 species of flatfish in a faster and less expensive manner than sequencing. This polymerase chain reaction-restriction fragment length polymorphism methodology (PCR-RFLP) was tested using commercial samples.