Note
While most gymnolaemates are restricted to waters of normal salinity, at least 3–6% are able to penetrate some distance into mixohaline water. Of this group, which includes 9 species of cyclostomes, 35 species of ctenostomes, 55 species of anascan and 21 species of ascophoran cheilostomes, the cyclostomes and the ascophorans are least tolerant of diluted salinities, the ctenostomes and the anascans are most tolerant.