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ORIGINAL RESEARCH article

Front. Cell Dev. Biol.
Sec. Evolutionary Developmental Biology
Volume 12 - 2024 | doi: 10.3389/fcell.2024.1471983

First Photon-Counting Detector Computed Tomography in the Living Crocodile: A 3D-Imaging Study with Special Reference to Amphibious Hearing

Provisionally accepted
Karl-Gunnar Melkersson Karl-Gunnar Melkersson 1Hao Li Hao Li 2Helge Rask-Andersen Helge Rask-Andersen 2*
  • 1 Kolmårdens Tropicarium AB, 618 93 Kolmården, Sweden, Kolmården, Sweden
  • 2 Department of Surgical Sciences, Faculty of Medicine, Uppsala University, Uppsala, Sweden

The final, formatted version of the article will be published soon.

    Background: Crocodiles are semi-aquatic animals well adapted to hear both on land and under water. Currently, there is limited information on how their amphibious hearing is accomplished. Here, we describe, for the first time, the ear anatomy in the living crocodile using photon-counting detector computed tomography (PCD-CT) and 3D rendering. We speculate on how crocodiles, despite their closed ear canals, can use tympanic hearing in water that also provides directional hearing Material and Methods: A Cuban crocodile (Crocodylus rhombifer) underwent photon-counting detector computed tomography (PCD-CT), under anesthesia and spontaneous respiration. In addition two seven-month-old C. rhombifer and a juvenile Morelet´s crocodile (Crocodylus moreletii) underwent micro-computed tomography (µCT) and endoscopy. One adult Cuviérs dwarf caiman (Paleosuchus palpebrosus) was micro-dissected and video-recorded. Aeration, earflap, and middle ear morphology were evaluated and compared after 3D modeling. Results and Discussion: PCD-CT and µCT with 3D rendering and segmentation demonstrated the anatomy of the external and middle ears with high resolution in both living and expired crocodiles. Based on the findings and comparative examinations, we suggest that the superior earflap, by modulating the meatal recess together with local bone conduction, may implement tympanic hearing in submerged crocodiles, including directional hearing.

    Keywords: photon-counting computed tomography, µCT, crocodiles, Hearing, underwater

    Received: 28 Jul 2024; Accepted: 09 Oct 2024.

    Copyright: © 2024 Melkersson, Li and Rask-Andersen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Helge Rask-Andersen, Department of Surgical Sciences, Faculty of Medicine, Uppsala University, Uppsala, Sweden

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.