Early development of the cephalic skeleton of Barbus barbus (Teleostei, Cyprinidae)

Abstract

The inception, and development of the cephalic skeleton of Barbus barbus from hatching to 24 days passes through periods of fast and slow growth; these rates are not the same in different parts of the skull. Trabeculae, parachordal plates, Meckelian cartilages and hyposymplecrics are present at hatching. Then the cartilaginous floor of the neurocranium develops, the pars quadrata, the hyoid bars and branchial arches elements appear shortly before the first movable dermal bones, the den taries, maxillae and opercles. The first bone of the braincase to appear is the parasphenoid; other bones develop subsequently and at the same time: the angular, quadrate, interopercle and fifth ceratobranchial. Later the splanchnocranium continues to develop at a relatively fast rate while the neurocranium shows little growth. The braincase does not begin to close before the 24th day, nor do the first bones of the skull roof appear, while the bucco-pharyngeal apparatus is complete, having the adult shape. The early constitution of the latter structures seems to be linked with the mechanical demands of biological functions such as breathing and feeding.

Embryonic Development and Skeletogenesis of the Pharyngeal Jaw Apparatus in the Cichlid Nile Tilapia (Oreochromis niloticus)

“…Functional needs have often been implicated in the ossification sequence of the teleostean skeleton (Vandewalle et al, 1992;Cubbage and Mabee, 1996;Mabee and Trendler, 1996). Bones involved in early functions such as respiration and feeding have generally been observed to ossify first.…”

An Experimental Study of Intraspecific Variation, Developmental Timing, and Heterochrony in Fishes

“…Conserved ossification sequences are expected on functional grounds, with mechanical stress on the early-functioning parts of the skeleton the proximate cause of skeletal ossification (Weisel 1967;Verraes 1975;Mook 1977;Morris and Gaudin 1982;Strauss 1992;Vandewalle et al 1992). The hypothesis that the sequence of ossification is constrained due to functional considerations, however, has not been quantitatively tested.…”

“…For Barbus there was no statistical difference in the timing of ossification of lateral line-associated dermal bones and bones not associated with the lateral line (Z ϭ 0.97, P Ͼ 0.33), but the trend was for lateral line-associated bones to appear later (Table 4). It is possible that our test was not powerful enough to detect differences between lateral line-associated and other bones in Barbus because several ties existed in the 34-bone dataset (extracted from Vandewalle et al 1992), and ties tend to reduce power (Zar 1999).…”

“…Intraspecific variation in ossification order was previously observed in only one other species, Betta splendens (referred to herein as Betta; Mabee and Trendler 1996), and thus interspecific comparisons of magnitude of variation in rank order could thus be made with only Betta. Data on cranial ossification sequences were available from two other species: Oryzias latipes (referred to herein as Oryzias; Langille and Hall 1987) and Barbus barbus (referred to herein as Barbus; Vandewalle et al 1992).…”

“…Betta splendens were reared at 28.5ЊC. Data for Oryzias latipes (Langille and Hall 1987) and Barbus barbus (Vandewalle et al 1992) dermal x ϭ 1.74 Ϯ 0.323 rank shifts/bone) and 28.5ЊC (Z ϭ Ϫ2.05, P Ͻ 0.05; cartilage x ϭ 2.45 Ϯ 0.265, dermal x ϭ 1.592 Ϯ 0.279 rank shifts/bone) and at all three temperatures combined (Z ϭ Ϫ2.50, P Ͻ 0.02; cartilage x ϭ 2.64 Ϯ 0.168, dermal x ϭ 1.86 Ϯ 0.244 rank shifts/bone). At 30.5ЊC the variation in the magnitude of rank differences was not statistically different between cartilage and dermal bones (Z ϭ Ϫ1.08, P Ͼ 0.27), but as at 26.5ЊC and 28.5ЊC, cartilage bones tended to be more variable (x ϭ 2.84 Ϯ 0.285 rank shifts/bone) than dermal bones (x ϭ 2.26 Ϯ 0.364 rank shifts/ bone; see Fig.…”