The interactive key includes 24 hesionid genera, based on diagnoses from Pleijel (1998), plus Hesionides and Microphthalmus. (Hesionides and Microphthalmus (both interstitial forms), were removed from the Hesionidae by Pleijel & Dahlgren (1998); however, those authors made no new family assignment so they are provisionally listed here with Hesionidae.) Thirteen Australian species, representing 9 genera, are also included. Hesionids are very fragile and are are typically poorly preserved, especially in samples from large environmental surveys. Many early descriptions of Hesionidae are also inadequate. For these reasons, the interactive key excludes a number of hesionids nominally recorded from Australia, and many taxa undoubtedly remain to be described from Australian waters (see the checklist for all nominal hesionid records from Australia). Therefore, the species descriptions in this database (all by R.Wilson) should be seen as only an interim attempt to document the Australian hesionid fauna.