Relative growth, sexual maturity and handedness in the ghost shrimp &lt;em&gt;Callichirus major&lt;/em&gt; (Decapoda: Callianassidae) from the southwestern Atlantic

Juliana Priscila Piva Rio,Patricio Hernáez,Marcelo Antonio Amaro Pinheiro

doi:10.3989/scimar.04869.28a

Relative growth, sexual maturity and handedness in the ghost shrimp <em>Callichirus major</em> (Decapoda: Callianassidae) from the southwestern Atlantic

Juliana Priscila Piva Rio, Patricio Hernáez + Show 1 more

Open Access

https://doi.org/10.3989/scimar.04869.28a

Copy DOI

Abstract

Biometric studies provide valuable information about changes associated with the growth and sexual maturity of living organisms. We analysed sexual dimorphism, allometric growth, sexual maturity and handedness in the ghost shrimp Callichirus major at Gonzaga beach, Brazil, where the catches of this species have been prohibited since 1992. To this end, a total of 544 individuals of C. major were collected during 12 months of sampling. Males were significantly smaller than females, denoting sexual dimorphism with respect to body size. The analysis of allometric growth between chelar carpus length and carapace length (CL) revealed a positive allometric relationship in juveniles of both sexes and adult males, but a negative allometry in adult females. Overall, our results showed the existence of two main growth phases related to sexual maturity, with a similar transition point for males (15.0 mm CL) and females (16.0 mm CL). Heterochely and homochely were registered in shrimp from both sexes, but in males heterochely occurred to a higher degree and was predominant (86.9%), whereas in females homochely was slightly more frequent (59.3%). The consequences of sexual dimorphism in terms of body size and chelipeds in the mating system of C. major are discussed in this study.

Highlights

In function of their feeding and behavioural interactions, crustaceans may have specialized claws as a first pair of pereopods (Mariappan et al 2000). Hartnoll (1974, 2012) mentions a chelar difference in most decapod crustaceans, generally more pronounced in males, which use it in agonistic interactions related to territorial defence or during competition for sexual partners
Such growth patterns are specific to each species and vary as a function of development phase of each sex, generating two discontinuous phases of growth and two different levels of allometric coefficients that define the moment of the morphological sexual maturity in decapods (Pinheiro and Fransozo 1998, Pardal-Souza and Pinheiro 2013)
A total of 544 specimens of C. major were collected during the study period, of which 162 (29.8%) were males and 382 (70.2%) females, including 166 ovigerous females

Summary

Introduction

In function of their feeding and behavioural interactions, crustaceans may have specialized claws as a first pair of pereopods (Mariappan et al 2000). Hartnoll (1974, 2012) mentions a chelar difference (heterochely) in most decapod crustaceans, generally more pronounced in males, which use it in agonistic interactions related to territorial defence or during competition for sexual partners. According to Hartnoll (1982), when a dependent variable (e.g. claw size or abdominal article) is related to an independent variable (e.g. body size), growth rate can be obtained by allometric coefficient (‘b’ constant), generating an isometry (b=1) or allometry (positive b>1 and negative b

Methods

Results

Discussion

Conclusion