The teeth are shed once (milk teeth) during the animal's lifetime or not at all, as is the case in cetaceans.
ðə tˈiːθ ɑːɹ ʃˈɛd wˈʌns mˈɪlk tˈiːθ dˈʊɹɹɪŋ ðɪ ˈænɪməlz lˈaɪftaɪm ɔːɹ nˌɑːt æɾ ˈɔːl, ˌæzˌɪz ðə kˈeɪs ɪn sɪtˈeɪʃənz.