Ultrastructure aspects of Brycon gouldingi (Teleostei, Characidae) related to swimming ability and feeding during larval development

Abstract

The larval ultrastructure of Brycon gouldingi related to swimming and feeding from hatching to total yolk absorption is described from scanning electron micrographs. Newly hatched larvae (time zero) had no mouth opening, undefined optic vesicles, an olfactory plate visible as a shallow depression, rudimentary gill arches, neural groove, embryonic fin and a primary neuromast in the dorsal region of the head. At the time of yolk absorption, 55 h post hatching, the larvae presented an optic vesicle comprising an optic cup and crystalline lens; a mouth with tongue, tapered teeth and taste buds; a ciliated olfactory cavity; branched gill arches; filled neural groove signalling central nervous system development; caudal, pectoral, dorsal and anal fins; and neuromasts distributed throughout the head and body. These characters are related to prey capture and swimming ability, key aspects of survival during the larval stage. The results of this study provide important information for exploitation and aquaculture of B. gouldingi.

Larval development of Brycon amazonicus (Teleostei, Bryconidae) with a focus on locomotory, respiratory and feeding structures

“…The olfactory plate lined with ciliated epithelium early in the development of B. amazonicus was also observed in larvae of other teleosts such as S. melanostictus (Matsuoka, ), Thunnus orientalis (Temminck & Schlegel 1844) (Kawamura et al ., ) and Brycon gouldingi Lima 2004 (Faustino et al ., ). According to these authors, the epithelium consisted mainly of three cell types: sensory cilia cells, receptor cells with numerous short microvilli and non‐sensory cilia cells.…”

“…In B. amazonicus these lamellae were arranged as rosettes in parallel, as described in Sardinops melanostictus (Temminck & Schlegel 1846)(Matsuoka, 2001) Uyan et al (2006). verified in Engraulis japonicus Temminck & Schlegel 1846 that each lamella is covered by a sensory epithelium at the base and lateral sides, with no epithelium on the borders; they suggest that this type of structure indicates that the fish possesses high olfactory acuity.The olfactory plate lined with ciliated epithelium early in the development of B. amazonicus was also observed in larvae of other teleosts such as S. melanostictus(Matsuoka, 2001), Thunnus orientalis (Temminck & Schlegel 1844)(Kawamura et al, 2003) and Brycon gouldingi Lima 2004(Faustino et al, 2018b). According to these authors, the epithelium consisted mainly of three cell types: sensory cilia cells, receptor cells with numerous short microvilli and non-sensory cilia cells.…”

“…In most teleost species, newly hatched larvae have no mouth, intestines, anus, gills, swimming bladder, fins, pigmentation or visual acuity (Faustino et al ., ; Marques et al ., ; Sampaio et al ., ). Differential development times for these systems follow ontogenetic patterns that vary between species and determine when a fish will acquire the ability to swim, escape and capture their own food (Faustino et al ., ). Thus, early feeding and survival success depends on the progressive development of anatomical characteristics, physiological functions and on the availability of suitable food items throughout larval development until the juvenile period, when a fish takes on characteristics similar to those of adults (Rønnestad et al ., ).…”

“…In most teleost species, newly hatched larvae have no mouth, intestines, anus, gills, swimming bladder, fins, pigmentation or visual acuity (Faustino et al, 2018a;Marques et al, 2017;Sampaio et al, 2015). Differential development times for these systems follow ontogenetic patterns that vary between species and determine when a fish will acquire the ability to swim, escape and capture their own food (Faustino et al, 2018b).…”

“…Nevertheless, ontogenetic changes in the digestive tract can lead to limitations in a fish's ability to process certain foods (Rønnestad et al, 2013). Studies of the functional importance of structures during development are scarce and should be further explored and focused on changes related to vital functional requirements, such as locomotion, feeding and respiration (Faustino et al, 2018b;Sahlmann et al, 2015;Silva et al, 2017). A better understanding of digestive tract formation, for example, can help to recognize factors affecting larviculture success and thus increase survival during this phase (Gisbert et al, 2004).…”