Ontogenetic Changes in the Morphology and Morphometry of Cuban Gar (Atractosteus tristoechus)

Abstract

Detailed examination of early development and growth of Cuban gar (Atractosteus tristoechus) was conducted using morphologic and morphometric characters. Larvae were reared at a constant water temperature (28 ± 1°C) from hatching to 18 days after hatching (DAH). Observation of the disappearance, reduction, or appearance of external structures, pigment characteristics, and behavior, identified three developmental stages (attached 0-3 DAH; transitional 4-10 DAH; and free-swimming 11-18 DAH). For the 18 day trial, the average growth rate was 1.30 mm/d and the specific growth rate averaged 10.2%/d. The slowest growth rates (0.02 mm/d and 2.8%/d, 7-11 DAH) coincided with the exhaustion of yolk reserves and the transition from endogenous to exogenous feeding. In addition to the slowest growth rates, the most dramatic morphological changes in A. tristoechus were observed during the transition from endogenous to exogenous feeding. Five total length (TL) groupings were established using 25 morphologic and morphometic characters. The characters snout length, pelvic fin length, snout width at nares, head length, and head width best identified length groupings. As the larvae developed, the snout and head lengthened and narrowed. Proportionally, the snout was narrower and the head longer in Cuban gar larvae than in other lepisosteid larvae.

Posthatch Development of Otoliths and Daily Ring Genesis in Age‐0 Spotted Gars

“…; Comabella et al. ). After 3–5 dph, gars have exhausted most of the yolk sac and absorbed the suctorial disk, and the jaw and fins have developed sufficiently to allow for horizontal positioning and active exogenous feeding (Mendoza et al.…”

“…Gars spawn in shallow areas of rivers and lakes, often around vegetation upon which the eggs adhere (Echelle and Riggs 1972;Simon and Tyberghein 1991). Eggs hatch in 3-5 d depending on temperature, and newly hatched gars have an adhesive sucker disk snout, which they use to attach to vegetation in a vertical position for further development Comabella et al 2010). After 3-5 dph, gars have exhausted most of the yolk sac and absorbed the suctorial disk, and the jaw and fins have developed sufficiently to allow for horizontal positioning and active exogenous feeding Comabella et al 2010;Frenette and Snow 2016;.…”

“…Eggs hatch in 3-5 d depending on temperature, and newly hatched gars have an adhesive sucker disk snout, which they use to attach to vegetation in a vertical position for further development Comabella et al 2010). After 3-5 dph, gars have exhausted most of the yolk sac and absorbed the suctorial disk, and the jaw and fins have developed sufficiently to allow for horizontal positioning and active exogenous feeding Comabella et al 2010;Frenette and Snow 2016;. Taken in context, the otoliths, which control Yes 1148 equilibrium and hearing, appear to develop their full functionality in gars just as their other organs do during the transition from vertical, attached larvae to horizontal, free-swimming juveniles.…”

Morphometric comparisons of the Gulf sturgeon (Acipenser oxyrinchus desotoiMitchill, 1815) in western and eastern population extremes

“…This juvenile form may have a functional use for estuarine feeding and shorter and more local movement demands, supporting previous findings of Atlantic, Gulf, and European sturgeon juveniles utilizing different migration patterns and habitats compared to adults (Lepage et al., ; Nellis et al., ; Sulak et al., ). Other species such as paddlefish and gars have been shown to exhibit functional shifting in head morphology with age class progression (Hoover et al., ; Comabella et al., ).…”

Embryonic Development of Cuban Gar (Atractosteus tristoechus) Under Laboratory Conditions

“…Its larval development was first described by Comabella et al. (, , ) from specimens reared under laboratory conditions. This vulnerable species could be a promising candidate species for aquaculture, because of its high growth rate and good adaptability to culture conditions.…”