Musculoskeletal anatomy and feeding performance of pre-feeding engyodontic larvae of the European eel (Anguilla anguilla).
Being part of the elopomorph group of fishes, Anguillidae species show a leptocephalus larval stage. However, due to largely unknown spawning locations and habitats of their earliest life stages, as well as their transparency, these Anguilla larvae are rarely encountered in nature. Therefore, information regarding the early life history of these larvae, including their exogenous feeding strategy and feeding performance, is rather scarce. To better understand the structural basis and functional performance of larval feeding in captivity, the functional morphology of the cranial musculoskeletal system in pre- and first-feeding engyodontic leptocephali of the European eel (Anguilla anguilla) was studied. A 3D reconstruction of the feeding apparatus (head of the leptocephali < 1 mm) was used to visualize and describe the musculoskeletal changes throughout these stages. To analyze the ontogenetic changes in the functionality of the feeding apparatus towards the active feeding phase, 3D data of joints, levers and muscles derived from the reconstructions were used to estimate bite and joint reaction forces (JRFs). Observing a maximum estimated bite force of about 65 μN (and corresponding JRFs of 260 μN), it can be hypothesized that leptocephalus larvae are functionally constrained to feed only on soft food particles. Additionally, potential prey items are size delimited, based on the theoretically estimated average gape of these larvae of about 100 μm. This hypothesis appears to be in line with recent observations of a diet consisting of small and/or gelatinous prey items (Hydrozoa, Thaliacea, Ctenophora, Polycystenia) found in the guts of euryodontic leptocephalus larvae.
Research Group Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium.
Mathias
M
Bouilliart
National Institute of Aquatic Resources - Section for Marine Ecology and Oceanography, Technical University of Denmark, Charlottenlund, Denmark.
Jonna
J
Tomkiewicz
Billund Aquaculture Service, Billund, Denmark.
Peter
P
Lauesen
Research Group Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium.
Barbara
B
De Kegel
Research Group Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium.
Dominique
D
Adriaens
D000811:Anguilla / Q000033:anatomy & histology / Q000502:physiology; D000818:Animals; D001696:Biomechanical Phenomena; D001732:Bite Force; D007568:Jaw / Q000033:anatomy & histology / Q000502:physiology; D007814:Larva / Q000033:anatomy & histology / Q000502:physiology; D008409:Mastication / Q000502:physiology*; D008410:Masticatory Muscles / Q000033:anatomy & histology / Q000502:physiology
Anguilla anguilla; bite force; engyodontic leptocephali; feeding performance; functional morphology