Neoteny occurs when the animal's growth rate is very low and is usually linked to adverse conditions such as low water temperatures that may change the response of the tissues to the hormone thyroxine.
nˈiːoʊtˌɛni əkˈɜːz wɛn ðɪ ˈænɪməlz ɡɹˈoʊθ ɹˈeɪt ɪz vˈɛɹi lˈoʊ ænd ɪz jˈuːʒuːəli lˈɪŋkt tʊ ædvˈɜːs kəndˈɪʃənz sˈʌtʃ ɐz lˈoʊ wˈɔːɾɚ tˈɛmpɹɪtʃɚz ðæt mˈeɪ tʃˈeɪndʒ ðə ɹᵻspˈɑːns ʌvðə tˈɪʃuːz tə ðə hˈoːɹmoʊn θˈaɪɹəksˌaɪn.