Growth and Sexual Maturity

Abstract

The pattern of somatic growth reflects the variable allocation of energy and materials throughout ontogeny, with direct impact on an individual’s fitness, and is therefore expected to be adaptive with regard to the different requirements of each life stage (Arendt 1997, Nylin and Gotthard 1998). The most straightforward way of studying growth trajectories is by building size-at-age structured models, which directly show the relationship of size increment over time (Smith and Botsford 1998). However, modelling crustacean growth presents particular challenges since size increments are restricted to the brief periods between moults, when the hard carapace is shed and the new cuticle remains soft. Crustacean growth is, therefore, best described as a discrete stepwise process where changes in size and shape occur abruptly, followed by a relatively long period with constant overall size and no changes in external morphology. Consequently, crustacean growth models require the estimation of 1) the increase in linear dimension at each moult or moult increment (MI) and 2) the time between moults or intermoult period (IP); as well their variation over time/age/size (Wainwright and Armstrong 1993, Hartnoll 2001, Chang et al. 2012).