Morphofunctional variations of the Echinometra lucunter (Echinoidea) on Bahia Coast, Brazil

Abstract

This study analyzes the morphometric aspects of two populations of Echinometra lucunter (Linnaeus, 1758) on Pituba and Itapuã beaches (Salvador, Bahia). Linear and volumetric measurements were performed on 117 specimens (test diameter > 40 mm) and the ratios between them were analyzed along with Aristotle's lantern weight participation (AL index). The potential model was tested between AL wet weight and tooth height (log data), estimating the coefficients by linear regression. Echinoid specimens from Pituba (n = 57) manifested a higher average degree of sphericity and test thickness. Proportionally, this population also showed higher AL and tooth height, indicating that the dimensions of this structure exhibit particularities in the spatial arrangement along the oral-aboral axis of the echinoids. Negative allometric relationships (β < 1) were observed in all specimens. The environments with distinct characteristics and wide food availability associated with a broad spectrum of the trophic niche occupied by the populations point out modulations and specializations of morphofunctional strategies and the expression of phenotypes.