Enormous gill chambers of deep-sea coffinfishes (Lophiiformes: Chaunacidae) support unique ventilatory specialisations such as breath holding and extreme inflation.

Deep sea habitats tend to favor species with low energetic demands, and therefore we predict that deep sea fishes will have behavioral and morphological specializations of the gill ventilatory system to reduce the energetic cost of pumping water across the gills. However, it is difficult to study functional morphology of deep sea fishes due the lack of ability to conduct laboratory experiments with living fishes. For this study, we combined analysis of publicly available video recorded by remote-operated vehicles (ROV) with detailed anatomical study of museum specimens to document the functional morphology of the massive gill chambers that are observed in coffinfishes (Lophiiformes: Chaunacidae).