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Rorqual whale nasal plugs: protecting the respiratory tract against water entry and barotrauma
- Source :
- Journal of Experimental Biology.
- Publication Year :
- 2020
- Publisher :
- The Company of Biologists, 2020.
-
Abstract
- The upper respiratory tract of rorquals, lunge-feeding baleen whales, must be protected against water incursion and against the risk of barotrauma at depth, where air-filled spaces like the bony nasal cavities may experience high adverse pressure gradients. We hypothesize these two disparate tasks are accomplished by paired cylindrical nasal plugs that attach on the rostrum and deep inside the nasal cavity. Here we present evidence that the large size and deep attachment of the plugs is a compromise allowing them to block the nasal cavities to prevent water entry while also facilitating pressure equilibration between the nasal cavities and ambient hydrostatic pressure (Pamb) at depth. We investigated nasal plug behaviour using videos of rorquals surfacing, plug morphology from dissections, histology, and MRI scans, and plug function by mathematically modelling nasal pressures at depth. We found each nasal plug has three structurally distinct regions: a muscular rostral region, a predominantly fatty mid-section, and an elastic tendon that attaches the plug caudally. We propose muscle contraction while surfacing pulls the fatty sections rostrally, opening the nasal cavities to air, while the elastic tendons snap the plugs back into place sealing the cavities after breathing. At depth, we propose Pamb pushes the fatty region deeper into the nasal cavities, decreasing air volume by about half and equilibrating nasal cavity to Pamb, preventing barotrauma. The nasal plugs are a unique innovation in rorquals that demonstrate their importance and novelty during diving, where pressure becomes as important an issue as the danger of water entry.
- Subjects :
- 0106 biological sciences
Nasal cavity
Physiology
Diving
Hydrostatic pressure
Aquatic Science
010603 evolutionary biology
01 natural sciences
03 medical and health sciences
biology.animal
otorhinolaryngologic diseases
medicine
Animals
14. Life underwater
Molecular Biology
Ecology, Evolution, Behavior and Systematics
030304 developmental biology
0303 health sciences
Air volume
biology
Whale
Whales
Anatomy
respiratory system
biology.organism_classification
medicine.anatomical_structure
Barotrauma
Insect Science
Animal Science and Zoology
Nasal Cavity
Rorqual
Large size
Geology
Water entry
Respiratory tract
Subjects
Details
- ISSN :
- 14779145 and 00220949
- Database :
- OpenAIRE
- Journal :
- Journal of Experimental Biology
- Accession number :
- edsair.doi.dedup.....3f4807fe346eebb8a6aa02be1239273b