title: Early development of marine catfishes (Ariidae): from mouth brooding to the release of juveniles in nursery habitats.
abstract: The development and allometric growth patterns of the ariid catfishes Cathorops spixii and Cathorops agassizii were studied from neurula embryos to juveniles. The ontogenetic sequence revealed that prior to hatching, embryos of both species are well developed, and their axial and appendicular skeletons are well ossified. Embryos of both species grow slowly longitudinally, but positively allometric growth (growth coefficient, β1 > 1) was observed in head width and eye diameter. It is hypothesized that these growth patterns might be related to functional priorities for the development of sensory organs, such as the inner ears (otoliths), the Weberian apparatus, eyes and nostrils, during the embryonic period. The first appearance of vertebrae and otoliths, as well as the ossification of otoliths and the Weberian apparatus, occur earlier in embryos of C. agassizii than in embryos of C. spixii. After hatching, mouth-brooded free embryos of both species grow isometrically. Negatively allometric growth was observed in head width and eye diameter during the yolk-sac period, which is expected given that the sensory organs are already formed. Free embryos of C. agassizii are distinguishable from those of C. spixii by their larger eyes, longer snouts, longer heads and heavier yolk sacs. The end of the yolk-sac period is characterized by a direct change from free embryo to juvenile, without a true larval period. The juveniles of the two species can also be distinguished from each other by the larger eyes of C. agassizii compared with C. spixii, as in adult fishes.
authors.affiliation: Department of Oceanography, Federal University of Pernambuco, Recife, Pernambuco, Brazil.
authors.forename: A R A
authors.initials: AR
authors.lastname: Lima
authors.forename: M
authors.initials: M
authors.lastname: Barletta
authors.forename: D V
authors.initials: DV
authors.lastname: Dantas
authors.forename: J A A
authors.initials: JA
authors.lastname: Ramos
authors.forename: M F
authors.initials: MF
authors.lastname: Costa
mesh_terms: D000818:Animals; D001938:Brazil; D002397:Catfishes / Q000033:anatomy & histology / Q000196:embryology / Q000254:growth & development*; D016000:Cluster Analysis; D017753:Ecosystem; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology; D047108:Embryonic Development; D063366:Estuaries; D005260:Female; D008018:Life Cycle Stages; D008297:Male; D012726:Sexual Behavior, Animal; D013045:Species Specificity