Positional and ontogenetic variation in vertebral centra morphology in five batoid species

Abstract

An increasing number of studies on elasmobranchs have shown that band-pair counts in vertebral centra do not accurately reflect age. Research in sharks has indicated that the number of band pairs vary with body size and that centrum morphology is related to structural needs. A study of this kind has not been undertaken on batoids; thus, we examined the relationship between band-pair deposition and morphology of centra along the vertebral column, and ontogenetically, for five batoid species (little skate, Leucoraja erinacea, winter skate, Leucoraja ocellata, barndoor skate, Dipturus laevis, Atlantic stingray, Dasyatis sabina, and round ray, Urobatis halleri). Centrum morphology and band-pair count varied along the vertebral column in all individuals of all species, except in young of the year. Variation in band-pair counts among centra within individuals supports the hypothesis that band-pair formation is related to somatic growth and body shape rather than to an annual cycle.