Functional Constraints on the Evolution of Larval Forms of Marine Invertebrates: Experimental and Comparative Evidence

Open Access
Publisher Website
Google Scholar
Abstract
Marine invertebrate larvae are well known for their distinctive body shapes and elaborate patterns of ciliation. In this study I take a physically based approach to investigate the functional consequences of variations in body shape and patterns of ciliation. With experimental models I demonstrate that shape as well as surface area contributes to drag of larval forms. Based on flow fields around larvae tethered in still water and flowing water I argue that drag, which acts as a partial tether, may influence how water is processed and food is captured by cilia. With mechanical models of cilia I show that placement of cilia on the surfaces can influence the effectiveness with which water is moved and the steepness of the velocity gradient through the ciliary layer. These models indicate that placement of cilia on ridges, at extreme anterior ends, and at extreme posterior ends of larval bodies increases the volume of water moved per ciliary stroke relative to placement of cilia on a flat surface. A comparative survey of46 larval forms indicates that distributions of body shape and patterns of ciliation reflect functional requirements of swimming and feeding by larvae. The experimental and comparative approaches together suggest functional constraints on the evolution of larval forms which may lead to convergence in patterns of ciliation and conservation of larval forms within taxa.

This publication has 0 references indexed in Scilit: