Using morphological and mitogenomic sequence data, Johnson et al. (2009) have shown that fishes formerly placed in the family Mirapinnidae
(tapetails) are actually the larvae of Cetomimidae
(whalefishes). These finding were very surprising since tapetails and whalefishes share very few morphological or ecological similarities. While the pelagic larvae live in the nutrient-rich habitat of the sunlit zone (above 200 m depth), adults are found only in the nutrient-poor waters of the bathypelagic realm (1000–4000 m). Metamorphosis from larva to adult involves dramatic changes in the skeleton, especially
the head, which are associated with distinctly different feeding mechanisms.