Meeting Abstract
Teleost fishes display a remarkable diversity of both body shapes and locomotor strategies. One fundamental aspect of fish shape is body elongation. Elongation is often expressed as the ratio of axial length to width or depth of the body. The elongation ratio has been shown to be associated with axial bending produced during swimming, with more elongate species often generating deeper and/or more numerous bends along the body axis. Elongation varies not only among species but also within individuals through their development. This study aimed to identify trends in body shape change by quantifying body elongation at larval and adult stages across a wide range of fish clades. Based on developmental work in several species, we hypothesized that most teleost fish would exhibit a decrease in elongation ratio through development. Using images from the literature and online image databases (e.g. fishbase), we have measured elongation ratio (axial length relative to depth) at larval and adult stages of a morphologically diverse range of teleost fishes. Axial length was measured from the center of the eye to the end of the caudal fin. Depth was measured at the anus for larval stages and just anterior to the anal fin for adult stages. Our data, including measurements of 53 species from 17 orders, indicate a widespread decrease in elongation ratio across teleost fishes. Only a few anguilliform species demonstrate a prominent increase in elongation ratio. These results have implications for understanding the development of locomotor behaviors. They suggest that the axial locomotor systems of a broad diversity of fishes may undergo elongation-related changes through early life history. In addition, they demonstrate striking conservation of this body shape change across a wide array of teleosts.
