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Gil KN, Vogl AW, Shadwick RE. Anatomical mechanism for protecting the airway in the largest animals on earth. Curr Biol 2022; 32:898-903.e1. [PMID: 35063119 DOI: 10.1016/j.cub.2021.12.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 10/18/2021] [Accepted: 12/16/2021] [Indexed: 11/29/2022]
Abstract
Separation of respiratory and digestive tracts in the mammalian pharynx is critical for survival. Food must be kept out of the respiratory tract, and air must be directed into the respiratory tract when breathing.1 Cetaceans have the additional problem of feeding while underwater. Lunge-feeding baleen whales (rorquals) open the mouth while swimming at high speeds to engulf a volume of prey-laden water as large as their own body2 and experience tremendous forces as water floods the mouth. How the respiratory tract is protected in the pharynx during engulfment and while swallowing a massive slurry of tiny living prey remains unknown, despite its importance to survival. By dissecting adult and fetal fin whales, we determined that a large musculo-fatty structure passively seals the oropharyngeal channel. This "oral plug" is not observed in other animals, and its position indicates it must be shifted to allow swallowing; it is a part of the soft palate and can only shift posteriorly and dorsally. Elevation of the oral plug allows food transfer to the pharynx and protects the upper airways from food entry. The laryngeal inlet in the floor of the pharynx is sealed by laryngeal cartilages, and the muscular laryngeal sac moves upward into the laryngeal cavity, completely occluding the airway. The pharynx is dedicated to the digestive tract during swallowing, with no connection between upper and lower airways. These adaptations to facilitate swallowing were a critical development in the evolution of large body size in these, the largest animals on earth.
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Affiliation(s)
- Kelsey N Gil
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
| | - A Wayne Vogl
- Life Sciences Institute and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Robert E Shadwick
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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Toro F, Alarcón J, Márquez S, Capella J, Bahamonde P, Esperón F, Moreno-Switt A, Castro-Nallar E. Composition and structure of the skin microbiota of rorquals off the Eastern South Pacific. FEMS Microbiol Ecol 2021; 97:6179854. [PMID: 33749784 DOI: 10.1093/femsec/fiab050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 03/18/2021] [Indexed: 01/04/2023] Open
Abstract
Recent advances in high-throughput sequencing have enabled the large-scale interrogation of microbiota in the most diverse environments, including host-associated microbiota. This has led to the recognition that the skin microbiota of rorquals is specific and structurally different from that of the ocean. This study reveals the skin microbiome of 85 wild individuals along the Chilean coast belonging to Megaptera novaeangliae, Balaenoptera musculus and Balaenoptera physalus. Alpha diversity analysis revealed significant differences in richness and phylogenetic diversity, particularly among humpback whales from different locations and between blue and humpback whales. Beta diversity was partially explained by host and location but only accounting for up to 17% of microbiota variability (adjusted VPA). Overall, we found that microbiota composition was dominated by bacterial genera such as Cardiobacter, Moraxella, Tenacibaculum, Stenotrophomonas, Flavobacteria and Pseudomonas. We also found that no ASVs were associated with the three rorqual species. Up to four ASVs were specific of a location, indicating a great variability in the microbiota. To the best of our knowledge, this is the first report on the composition and structure of the skin microbiota of whales off the coast of Chile, providing a foundational dataset to understand the microbiota's role in rorquals.
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Affiliation(s)
- Frederick Toro
- Facultad de Ciencias de la Vida, Universidad Andres Bello, Center for Bioinformatics and Integrative Biology, Avenida Republica 330, Santiago 8370186, Chile.,Doctorate in Conservation Medicine, Facultad de Ciencias de la Vida, Universidad Andres Bello, Departamento de Ecologia y Recursos Naturales, Avenida Republica 330, Santiago 8370186, Chile.,Panthalassa, Red de Estudios de Vertebrados Marinos de Chile Toesca 2002 P6, Santiago, Chile.,Facultad de Medicina Veterinaria y Recursos Naturales, Universidad Santo Tomás, Escuela de Medicina Veterinaria, Avenida Limonares 190, Viña del Mar, Chile
| | - Jaime Alarcón
- Facultad de Ciencias de la Vida, Universidad Andres Bello, Center for Bioinformatics and Integrative Biology, Avenida Republica 330, Santiago 8370186, Chile
| | - Sebastián Márquez
- Facultad de Ciencias de la Vida, Universidad Andres Bello, Center for Bioinformatics and Integrative Biology, Avenida Republica 330, Santiago 8370186, Chile
| | - Juan Capella
- Whalesound Ltda., Lautaro Navarro 1163, 2do piso. Punta Arenas, Chile.,Fundación Yubarta, Apartado Aéreo 33141, Cali, Colombia
| | - Paulina Bahamonde
- Melimoyu Ecosystem Research Institute, Avenida Kennedy 5682, Vitacura, Chile.,Universidad de Playa Ancha, HUB AMBIENTAL UPLA - Centro de Estudios Avanzados, Playa Ancha 850, Valparaíso, Chile
| | - Fernando Esperón
- Animal Health Research Center, INIA-CISA, Valdeolmos, Carretera Algete-El Casar de Talamanca, Km. 8,1, 28130 Valdeolmos, Madrid, Spain
| | - Andrea Moreno-Switt
- Millennium Initiative for Collaborative Research on Bacterial Resistance (MICROB-R), Avenida Las Condes 12.461, torre 3, oficina 205. Las Condes, Chile.,Facultad de Medicina Veterinaria, Pontificia Universidad Católica de Chile
| | - Eduardo Castro-Nallar
- Facultad de Ciencias de la Vida, Universidad Andres Bello, Center for Bioinformatics and Integrative Biology, Avenida Republica 330, Santiago 8370186, Chile
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Abstract
The largest animals are baleen filter feeders that exploit large aggregations of small-bodied plankton. Although this feeding mechanism has evolved multiple times in marine vertebrates, rorqual whales exhibit a distinct lunge filter feeding mode that requires extreme physiological adaptations-most of which remain poorly understood. Here, we review the biomechanics of the lunge feeding mechanism in rorqual whales that underlies their extraordinary foraging performance and gigantic body size.
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Affiliation(s)
- Robert E Shadwick
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jean Potvin
- Department of Physics, Saint Louis University, St. Louis, Missouri
| | - Jeremy A Goldbogen
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, California
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Shadwick RE, Goldbogen JA, Pyenson ND, Whale JCA. Structure and Function in the Lunge Feeding Apparatus: Mechanical Properties of the Fin Whale Mandible. Anat Rec (Hoboken) 2018; 300:1953-1962. [PMID: 28971624 DOI: 10.1002/ar.23647] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 06/13/2017] [Accepted: 06/20/2017] [Indexed: 11/11/2022]
Abstract
The mandibles of rorqual whales are highly modified to support loads associated with lunge-feeding, a dynamic filter feeding mechanism that is characterized by rapid changes in gape angle and acceleration. Although these structures are the largest ossified elements in animals and an important part of the rorqual engulfment apparatus, details of internal structure are limited and no direct measurements of mechanical properties exist. Likewise, the forces that are sustained by the mandibles are unknown. Here we report on the structure and mechanical behavior of the mandible of an adult fin whale. A series of transverse sections were cut at locations along the entire length of a 3.6-m left mandible recovered post-mortem from a 16-m fin whale, and CT scanned to make density maps. Cored samples 6-8 mm in diameter were tested in compression to determine the Young's modulus and strength. In addition, wet density, dry density and mineral density were measured. Dense cortical bone occupies only a relatively narrow peripheral layer while much less dense and oil-filled trabecular bone occupies the rest. Mineral density of both types is strongly correlated with dry density and CT Hounsfield units. Compressive strength is strongly correlated with Young's modulus, while strength and stiffness are both correlated with mineral density. It appears that the superficial compact layer is the main load bearing element, and that the mandible is reinforced against dorso-vental flexion that would occur during the peak loads while feeding. Anat Rec, 300:1953-1962, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Robert E Shadwick
- Department of Zoology, University of British Columbia, British Columbia, V6T 1Z4, Canada
| | - Jeremy A Goldbogen
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - Nicholas D Pyenson
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - James C A Whale
- Department of Zoology, University of British Columbia, British Columbia, V6T 1Z4, Canada
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