Flying underwater: elucidating key insights into biological aspects of the whip-tail of Myliobatidae stingrays (manta, eagle and cownose rays)

• Applicant: Júlia Chaumel
• Subject Area: Systematics and Morphology (Zoology) ; Animal Physiology and Biochemistry ; Biomaterials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 510759809

Fishes are efficient swimmers with diversity of habitats and lifestyles. Among the varied fish locomotion modes, that of myliobatid stingrays —manta, eagle and cownose rays— is unique, involving flapping the pectoral fins like birds’. This mode allows myliobatids to actively swim in the water column, migrate long distances, and maneuver in complex landscapes. Equally unique and striking is the distinctive myliobatid tail, slender like a whip and ≤3x the animal’s body length. However, the biological significance and potential advantages of this massive appendage for locomotion and/or other functions have never been explored. In this resubmitted project, we will undertake the first biological characterization of the myliobatid whip-tail, in a multi-disciplinary analysis of its morphology, kinematics and hydrodynamics. First, through a deep bibliographic survey and museum specimen measurements, we will characterize tail morphometric variation across myliobatid species, across ontogeny, and how variation correlates with ecological factors. Second, we will determine the organization, composition, and mechanical properties of tissues forming the tail using histology, high-resolution imaging, and mechanical testing at different structural levels. Results will allow us to determine how much control the animal has over the tail and how flexible/stiff it is, capturing features relevant for hydrodynamics (e.g. ridges, denticles) or other functions (e.g. presence of sensory cells). Third, tail kinematics and hydrodynamics will be studied by quantifying tail movements and tail interactions with water flow through direct observation of animals swimming in aquaria. Integration of these results will allow transversal understanding of the biological significance of the myliobatid tail (e.g. in physiology, but also ecological data for management of endangered species); will reveal anatomical modifications involved in evolution of a novel appendage; and will inform design of next generation efficient, bio-inspired underwater vehicles.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professor George Lauder, Ph.D.