Dimorphism throughout the European eel's life cycle: are ontogenetic changes in head shape related to dietary differences?

Abstract

A well-known link exists between an organism's ecology and morphology. In the European eel, a dimorphic head has been linked to differences in feeding ecology, with broad-headed eels consuming harder prey items than narrow-headed ones. Consequently, we hypothesized that broad-heads should exhibit a cranial musculoskeletal system that increases bite force and facilitates the consumption of harder prey. Using 3D-reconstructions and a bite model, we tested this hypothesis in two life stages: the sub-adult yellow eel stage and its predecessor, the elver eel stage. This allowed us to test whether broad- and narrow-headed phenotypes show similar trait differences in both life stages and whether the dimorphism becomes more pronounced during ontogeny. We show that broad-headed eels in both stages have larger jaw muscles and a taller coronoid, which are associated with higher bite forces. This increased bite force together with the elongated upper and lower jaws in broad-headed eels can also improve grip during spinning behavior, which is used to manipulate hard prey. Head shape variation in European eel is therefore associated with musculoskeletal variation that can be linked to feeding ecology. However, although differences in muscle volume become more pronounced during ontogeny, this was not the case for skeletal features.

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

“…; De Meyer et al. ,c); the specimen used in this study was a broad‐headed individual, which are more piscivorous. The Esox specimen was micro (μ)CT scanned at the Imaging and Analysis Centre at the Natural History Museum (London, UK) on a X‐Tek HMX‐ST μCT 255 scanner (Nikon Metrology, Tring, UK) at 180 kV and 120 μA with a 0.5‐mm copper filter producing 1999 TIFF images with a resolution of 0.043 mm voxel −1 .…”

“…; Sharp & Trusler, ; Porro & Richards, ), but there are examples of contrast‐enhanced CT and ‘digital dissection’ of teleosts (De Meyer et al. 2018a). Although several studies have presented 3D reconstructions of teleost anatomy both graphically (Anker, ; Adriaens & Verraes, ,b) and digitally (Leysen et al.…”

“…As a result, contrast-enhanced CT scans have been used to 'digitally dissect' specimens, producing interactive three-dimensional (3D) virtual anatomical atlases (Holliday et al 2013;Lautenschlager et al 2014;Porro & Richards, 2017), and provide useful functional data on soft tissue, for example, muscle volumes (Cox & Faulkes, 2014;Sharp & Trusler, 2015). -ar, angulo-articular; ar, articular; bb, basibranchial; bh, basihyal; cha, anterior ceratohyal; chp, posterior ceratohyal; cm, coronomeckelian; co, circumorbital series; d, dentary; de, dermethmoid; de/v, fused dermethmoid and vomer; ep, epitotic; ept, ectopterygoid; fr, frontal; hy, hyomandibular; iop, inter-opercular; la, lacrimal; mc, Meckel's cartilage; mpt, metapterygoid; mx, maxilla; na, nasal; ne, neurocranium; op, opercular; p, parietal; pa, parasphenoid; pe, proethmoid; pfr, pre-frontal; pl, palatal; pmx, pre-maxilla; pmx/v, fused pre-maxilla and vomer; pop, pre-opercular; pr, pterotic; pt, pterygoid; q, quadrate; s, symphysis; smx, supra-maxilla; so, super-occipital; sop, sub-opercular; sp, sphenotic; uh, urohyal. To date, this method has mostly been applied to tetrapods (Cox & Jeffery, 2011;Holliday et al 2013;Lautenschlager et al 2014;Sharp & Trusler, 2015;Porro & Richards, 2017), but there are examples of contrast-enhanced CT and 'digital dissection' of teleosts (De Meyer et al 2018a).…”

Construction of environmental art aided design system based on digital technology application in Smart Energy Industries

“…These systems, however, not only demand highly con gured hardware but are also marketed at exorbitant prices. Companies like Martnez-Materialize Noya in Belgium started looking into software-only systems like Mimics [22], others like Able Software in the US [23], and Visage in Europe [24]. They all eliminate the hardware dependence of computer-aided systems and enable the execution of a variety of real-time tasks via integrated functions using Arti cial Intelligence.…”

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.…”