The heart has two chambers and pumps the blood through the respiratory surfaces of the gills and on round the body in a single circulatory loop.
ðə hˈɑːɹt hɐz tˈuː tʃˈeɪmbɚz ænd pˈʌmps ðə blˈʌd θɹuː ðə ɹˈɛspɹətˌoːɹi sˈɜːfɪsᵻz ʌvðə ɡˈɪlz ænd ˌɔn ɹˈaʊnd ðə bˈɑːdi ɪn ɐ sˈɪŋɡəl sˈɜːkjʊlətˌoːɹi lˈuːp.