"Designating aquatic invertebrates with concealed gills, especially certain nudibranch molluscs that are able to completely retract their gills; of or relating to such invertebrates", Mid 19th cent.; earliest use found in Richard Owen (1804–1892), comparative anatomist and palaeontologist. From crypto- + -branchiate. With sense 1 compare French cryptobranche.[cryptobranchiate etymology, cryptobranchiate origin, 英语词源]