Beak allometric growth of jumbo squid Dosidicus gigas (Orbigny, 1835) in Southeastern Pacific Ocean
DOI:
https://doi.org/10.54830/bmnhn.v67.n2.2018.32Keywords:
Jumbo squid, Dosidicus gigas, cephalopods, morphometry, allometry, ChileAbstract
The disproportionate growth of certain body structures is called allometry and its study has ecological and evolutionary implications. The hard structures of cephalopods (statoliths, gladius and beaks) have been used to observe and quantify age and growth in different species. Given the fast growth of these animals, the beaks are likely to have positive allometry. To evaluate this, 12 morphometric measurements of the lower and upper beaks of 66 squids of the species Dosidicus gigas captured in front of Chile during the spring of 2003 were performed. Univariate and multivariate statistical analyses were performed to demonstrate allometry of the beaks. The results of the univariate analyses showed that almost all (11/12) the morphometric measurements presented a positive allometry, in relation to the size of the squids. In the multivariate analyses, almost all (4/6) structures of the upper beak presented allometry, while the majority (4/6) of the structures of the lower beak presented isometry. This study provides evidence that the squid's beaks grow at different rates, allometrically in the upper beaks grow and isometrically in the lower beaks (except for the rostral length). This information would allow us to decide which of the beaks to use in studies of age and growth of squid, stomach content analysis, identification of species and comparison of populations.
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