Three species are now recognized; F. buelli, F. goedertorum, and F. humilis. Fucaia ''humilis is latest Eocene in age and thus the oldest mysticete in the Northern Hemisphere, F. buelli is of early Oligocene age, while F. goedertorum is younger. The latter was originally described as a species of Chonecetus before it was recognized as more closely related to buelli than to the Chonecetus'' type species.
Palaeobiology
The tooth structure of Fucaia indicates that it was capable of both raptorial feeding and suction-feeding, like other aetiocetids. Analysis of the cranium and postcranium of F. goedertorum has confirmed that the species was a suction-assisted raptorial feeder.