Molluscs are an extraordinarily diverse group of animals and to discriminate them based on one molecular marker/gene is very difficult because of the too fast or slow rate of nucleotide substitution. In the study, the tropomyosin cds (coding sequences) of 43 animal species were analyzed, the results of which suggested that the tropomyosin gene was a nice marker gene to phylogenetic analysis of molluscs, even for all the studied animals. In addition, InDels (insertions and deletions) in tropomyosin cds of turbo cornutus were also studied and one segment repeat, which probably happened recently and was of functional importance, was found.