| Summary: | Despite great interest in cetacean sound production, little is known about the trachea’s role. Tracheas were examined in 16 odontocete (toothed whale) and 7 mysticete (baleen whale) genera. Results indicate that all whales share incomplete ventral cartilage at the cranial end, but differ in lumen surfaces. Three patterns are observed: parallel tracheal folds (TF) in mysticetes, trabeculated surface (TS) in dolphins and porpoises, and smooth walled in sperm whales. TF and TS appear to direct airflow towards vocal folds, and thus may affect sound production. Sperm whales lack any texture, and their smooth wall correlates with a limited vocal repertoire. TF and TS may also enable stretch/recoil, thus accommodating pressure‐induced volume changes during diving/ascent. The incomplete ventral cartilage may also facilitate such volume contraction, as this portion of the tracheal wall is pliable. The mysticete trachea can accommodate even greater volume changes by collapsing the lumen along the midline. This deformation is not a complete collapse, as it preserves flow along the lateral spaces where TF are found. The trachea appears to have two major roles in most whale species: channeling airflow for sound production, and accommodating pressure‐induced volume changes during diving/ascent. The lack of TS in the deep diving sperm whales is puzzling, and warrants study of how they accommodate volume changes during diving. Grant Funding Source : Supported by NOAA Prescott Stranding Grant Program, and Office of Naval Research
|
|---|