Broader head, stronger bite: In vivo bite forces in European eel Anguilla anguilla

Abstract

This work examined three different phenotypes of the yellow-eel stage of the European eel Anguilla anguilla, broad-heads, narrow-heads and eels with an intermediate head shape. The aim was to see whether broad-headed A. anguilla, which generally consume harder, larger prey, such as crustaceans and fish, exerted greater bite force than the narrow-headed variant, which mainly consume soft, small prey such as chironomid larvae. It was found that in 99 yellow A. anguilla, in vivo bite force of broad-heads are higher compared with narrow-heads and intermediates.

A digital dissection of two teleost fishes: comparative functional anatomy of the cranial musculoskeletal system in pike (Esox lucius) and eel (Anguilla anguilla)

“…As a result, we would expect Anguilla to be capable of producing higher bite forces than Esox, particularly at low gape angles. This is in agreement with bite force data collected in vivo (Dutel et al 2015;De Meyer et al 2018b). By contrast, the longer fibres of Esox should permit a larger range of movement and wider gape angles.…”

“…; De Meyer et al. 2018b). By contrast, the longer fibres of Esox should permit a larger range of movement and wider gape angles.…”

“…Eels use biting as well as suction (Mehta & Wainwright, ,b) for capturing small prey, but rely on the production of high bite forces in order to remove pieces from large prey items and break into armoured small prey (Proman & Reynolds, ; De Meyer et al. ,c). Pike use suction to capture small prey (Rand & Lauder, ); large prey are initially drawn into the mouth by suction, then bitten into and grasped with the teeth, before being moved through the oral cavity and swallowed using subsequent suction events, resulting in a ratcheting effect (LB Porro, A Herrel, personal observations).…”

From yellow to silver: Transforming cranial morphology in European eel (Anguilla anguilla)

“…This cessation of feeding can have an impact on the morphology of the maturing eels, as dietary shifts are known to impact morphology in European eel (De Meyer et al ., 2016), as well as in other fish species (Svanbäck et al ., 2008; Svanbäck and Eklöv, 2002). The cranial morphology has been thoroughly studied at life stages preceding the silver eel stage (Bouilliart et al ., 2015; De Meyer et al ., 2018a, 2018b), and also bite force has previously been determined in these stages (De Meyer et al ., 2018a, 2018b, 2018c). To fully understand the eel's morphology during ontogeny, we here want to determine the cranial changes associated with silvering.…”

Unimodal head-width distribution of the European eel (Anguilla anguilla L.) from the Zeeschelde does not support disruptive selection

“…Still, many studies have dichotomously classified narrow and broad headed eels using a ratio-based threshold: eels with a head width over total body length ratio smaller than 0.033 are considered narrow heads, while eels with larger ratios are broad heads ( Barry et al., 2016 ; Kaifu et al., 2013 ; Lammens & Visser, 1989 ; Proman & Reynolds, 2000 ). However, head width increases allometrically with total length ( De Meyer et al., 2017a ; De Meyer et al., 2015 ; Lammens & Visser, 1989 ), so larger eels may be wrongly classified as broad heads.…”