PMC7671108_01
Average clasper lengths per individual plotted against disc width in male Fenestraja plutonia. The onset of sexual maturation is shown by a vertical dashed line segment that demarcates an inflection point after which clasper length rapidly increases.
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In skates, claspers undergo rapid elongation at the onset of sexual maturity, and in species like F. plutonia, the approximate body size at which this transition takes place can easily be identified by plotting clasper length against disc width (Fig. 2).
Measurements made on endoskeletal traits in F. plutonia (yellow lines).
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In the same specimens evaluated for external pectoral fin shape, we took X-rays and made linear measurements of several endoskeletal traits (Fig. 3).