Figure 2: Video images showing the key stages in the spiracular air-breath cycle for P. senegalus. | Nature Communications

Figure 2: Video images showing the key stages in the spiracular air-breath cycle for P. senegalus.

From: Spiracular air breathing in polypterid fishes and its implications for aerial respiration in stem tetrapods

Figure 2

(a) Head reaches and becomes parallel to the water surface. (b) Dorsal–ventral body diameter posterior of the pectoral fins is reduced with the ejection of air from the lungs into the buccopharyngeal chamber (which expands) and out the opercula. (c) Compression of the buccopharyngeal and opercular chambers expels additional lung air out the opercular openings. (d) The spiracular valves open above the water surface resulting in air aspiration into the buccopharyngeal chamber (which expands) and lungs (as indicated by an increase in dorsal–ventral body diameter). (e) Spiracular valve closure is rapidly followed by the compression of the buccopharyngeal chamber, which forces additional air into the lungs, further expanding dorsal–ventral body diameter. (f) As the fish leaves the surface, the gills are ventilated with water, which clears unused air from the buccopharyngeal chamber out the opercular slits. (See Supplementary Movie 3 for complete footage associated with these still images).

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