Their gills are never covered by gill sacs and are reabsorbed just before the animals leave the water.
ðɛɹ ɡˈɪlz ɑːɹ nˈɛvɚ kˈʌvɚd baɪ ɡˈɪl sˈæks ænd ɑːɹ ɹˈiːbsoːɹbd dʒˈʌst bᵻfˌoːɹ ðɪ ˈænɪməlz lˈiːv ðə wˈɔːɾɚ.