Genome size distribution in phylum Cnidaria

Cnidarians are considered ancestral metazoans and, therefore, are important taxa for studying animal evolution. However, little is known about the group’s genome size (C value), which is an important parameter in whole-genome sequencing. To address this issue, we measured the C values of 27 cnidarian species from Japan, using flow cytometry, and found that they ranged from 0.26 to 3.56 pg. Excluding the results for Agalma elegans and Physalia physalis (order Siphonophorae), which had the highest C values among the species included in the present study, the C values for the cnidarians were 0.26–1.49 pg. In particular, we found that hydrozoans possessed relatively large and wide-ranging C values, indicating that evolution within the group involved considerable gains or losses of genomic content. Overall, the C values reported in the present study could be valuable for whole-genome sequencing, using next-generation sequencers, and for future research in cytogenetics.