1
|
van Meer NMME, Weller HI, Manafzadeh AR, Kaczmarek EB, Scott B, Gussekloo SWS, Wilga CD, Brainerd EL, Camp AL. Intra-oropharyngeal food transport and swallowing in white-spotted bamboo sharks. ACTA ACUST UNITED AC 2019; 222:jeb.201426. [PMID: 31672726 DOI: 10.1242/jeb.201426] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 10/23/2019] [Indexed: 01/26/2023]
Abstract
Despite the importance of intraoral food transport and swallowing, relatively few studies have examined the biomechanics of these behaviors in non-tetrapods, which lack a muscular tongue. Studies show that elasmobranch and teleost fishes generate water currents as a 'hydrodynamic tongue' that presumably transports food towards and into the esophagus. However, it remains largely unknown how specific musculoskeletal motions during transport correspond to food motion. Previous studies of white-spotted bamboo sharks (Chiloscyllium plagiosum) hypothesized that motions of the hyoid, branchial arches and pectoral girdle, generate caudal motion of the food through the long oropharynx of modern sharks. To test these hypotheses, we measured food and cartilage motion with XROMM during intra-oropharyngeal transport and swallowing (N=3 individuals, 2-3 trials per individual). After entering the mouth, food does not move smoothly toward the esophagus, but rather moves in distinct steps with relatively little retrograde motion. Caudal food motion coincides with hyoid elevation and a closed mouth, supporting earlier studies showing that hyoid motion contributes to intra-oropharyngeal food transport by creating caudally directed water currents. Little correspondence between pectoral girdle and food motion was found, indicating minimal contribution of pectoral girdle motion. Transport speed was fast as food entered the mouth, slower and step-wise through the pharyngeal region and then fast again as it entered the esophagus. The food's static periods in the step-wise motion and its high velocity during swallowing could not be explained by hyoid or girdle motion, suggesting these sharks may also use the branchial arches for intra-oropharyngeal transport and swallowing.
Collapse
Affiliation(s)
- Noraly M M E van Meer
- Experimental Zoology Group, Wageningen University, PO Box 338, NL-6700 AH Wageningen, The Netherlands
| | - Hannah I Weller
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| | - Armita R Manafzadeh
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| | - Elska B Kaczmarek
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| | - Bradley Scott
- Department of Evolution, Ecology, and Behavior, University of Illinois, Urbana-Champaign, Victor E. Shelford Vivarium, Champaign, IL 61820, USA
| | - Sander W S Gussekloo
- Experimental Zoology Group, Wageningen University, PO Box 338, NL-6700 AH Wageningen, The Netherlands
| | - Cheryl D Wilga
- Department of Biological Sciences, University of Alaska Anchorage, 3101 Science Circle, Anchorage, AK 99508, USA
| | - Elizabeth L Brainerd
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| | - Ariel L Camp
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.,Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool L7 8TX, UK
| |
Collapse
|
2
|
Scott B, Wilga CAD, Brainerd EL. Skeletal kinematics of the hyoid arch in the suction-feeding shark Chiloscyllium plagiosum. ACTA ACUST UNITED AC 2019; 222:222/5/jeb193573. [PMID: 30824570 DOI: 10.1242/jeb.193573] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 01/08/2019] [Indexed: 11/20/2022]
Abstract
White-spotted bamboo sharks, Chiloscyllium plagiosum, generate strong suction-feeding pressures that rival the highest levels measured in ray-finned fishes. However, the hyostylic jaw suspension of these sharks is fundamentally different from the actinopterygian mechanism, including more mobile hyomandibulae, with the jaws and ceratohyal suspended from the hyomandibulae. Prior studies have proposed skeletal kinematics during feeding in orectolobid sharks from indirect measurements. Here, we tested these hypotheses using XROMM to measure cartilage motions directly. In agreement with prior hypotheses, we found extremely large retraction and depression of the ceratohyal, facilitated by large protraction and depression of the hyomandibula. Somewhat unexpectedly, XROMM also showed tremendous long-axis rotation (LAR) of both the ceratohyal and hyomandibula. This LAR likely increases the range of motion for the hyoid arch by keeping the elements properly articulated through their large arcs of motion. XROMM also confirmed that upper jaw protraction occurs before peak gape, similarly to actinopterygian suction feeders, but different from most other sharks in which jaw protrusion serves primarily to close the mouth. Early jaw protraction results from decoupling the rotations of the hyomandibula, with much of protraction occurring before peak gape with the other rotations lagging behind. In addition, the magnitudes of retraction and protraction of the hyoid elements are independent of the magnitude of depression, varying the shape of the mouth among feeding strikes. Hence, the large variation in suction-feeding behavior and performance may contribute to the wide dietary breadth of bamboo sharks.
Collapse
Affiliation(s)
- Bradley Scott
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA .,Department of Animal Biology, University of Illinois Urbana-Champaign, Victor E. Shelford Vivarium, Champaign, IL 61820, USA
| | - Cheryl A D Wilga
- Department of Biological Sciences, University of Rhode Island, 120 Flagg Road, Kingston, RI 02881, USA.,Department of Biological Sciences, University of Alaska Anchorage 3101 Science Circle, Anchorage, AK 99508, USA
| | - Elizabeth L Brainerd
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA
| |
Collapse
|