ɪɹˈɛθɪstˌɪdz dˈɪfɚ fɹʌm æmblˈɪsɪpˌɪɾɪdz ɪn ðæt ðeɪ lˈæk ɐ kˈʌplaɪk fˈoʊld ʌv skˈɪn ɪn fɹˈʌnt ʌvðə pˈɛktɚɹəl fˈɪn vˌiːˈɛs. pəzˈɛsɪŋ ðə kˈʌplaɪk fˈoʊld, ænd hæv ɐ dˈoːɹsəl fˈɪn wɪð ɐ stɹˈɔŋ spˈaɪn ænd nˈoʊ θˈɪk kˈʌvɚɹɪŋ ʌv skˈɪn vˌiːˈɛs. ɐ wˈiːk spˈaɪn wɪð ɐ θˈɪk kˈʌvɚɹɪŋ ʌv skˈɪn.
Erethistids differ from amblicipitids in that they lack a cuplike fold of skin in front of the pectoral fin (vs. possessing the cuplike fold), and have a dorsal fin with a strong spine and no thick covering of skin (vs. a weak spine with a thick covering of skin).