Pleuronectidae and they sink to the bottom. They are found on the bottoms of oceans around the world, with some species, such as the Atlantic halibut, "Hippoglossus hippoglossus", being found down to . The smaller species eat sea-floor invertebrates such as polychaetes and crustaceans, but the larger righteye flounders, such as "H. hippoglossus", which grows up to in length, feed on other fishes and cephalopods, as well. They include many important commercially fished species, including not only the various fish called flounders, but also the European plaice, the halibuts, the lemon sole, the common dab, the Pacific Dover sole, and the
IsomiR isomiRs have been detected deregulated in D. melanogaster development and differential expressed during "Hippoglossus hippoglossus" L. early development, suggesting a biologically relevant function. IsomiR isomiR is a term coined by Morin et al. to refer to those sequences that have variations with respect to the reference miRNA sequence. miRBase is considered to be the gold-standard miRNA database—it stores miRNA sequences detected by thousand of experiments. In this database each miRNA is associated with a miRNA precursor and with one or two mature miRNA (-5p and -3p). Similarly, VIRmiRNA is the only available resource for miRNA in the field of virus.