Ontogeny of swimming movements in bronze corydoras (Corydoras aeneus)

Abstract

Fish larvae experience fundamental morphological, physiological, and physical changes from hatching to adulthood. All of these changes have an effect on the locomotor movements observed in the larvae. We describe the development of swimming movements in larval bronze corydoras (Corydoras aeneus (Gill, 1858); Ostariophysi, Siluriformes) during their ontogeny. Swimming movements of adults and larvae, aged 0-512 h posthatching, were recorded at 500 frames/s. Movements were analyzed by digitizing points along the fish midline. Movements are described by direct (swimming speed and amplitude of landmarks) and indirect (r 2 mean and CV of r 2 as movement coordination indices; Strouhal number as an efficiency index) parameters. The increase in swimming speed correlated with improvement of movement coordination in both larvae and adults, as well as with an increase in swimming efficiency in larvae. Directly after hatching, swimming movements were coordinated but were not efficient. Efficiency increased rapidly with fish growth up to 8 mm total fish length and disappearance of the yolk sac. These events were coupled with reduction of the maximal lateral amplitude observed along the whole body during swimming. The anguilliform swimming mode was used at hatching, but a transition to the carangiform mode was observed at approximately 17 mm total fish length.

The origins of adipose fins: an analysis of homoplasy and the serial homology of vertebrate appendages

“…Our result, that adipose fins have evolved repeatedly, is based on the phylogenetic hypothesis of Near et al [34] and appears robust relative to minor topological changes among euteleosts [35]. A few analyses have found Characiformes to be paraphyletic, with Siluriformes nested within Characiformes [53,54]. Although our analysis does not include trees of this topology, characiform paraphyly is unlikely to change our result.…”

Mechanosensation in an adipose fin

“…) found that lateral excursion of the trunk at the position of the adipose fin did not exceed 1.0 mm [17].…”

“…The probe, a pinhead, was mounted to the end of a voice coil positioning stage (VCS10-023-BS-01-M, H2 W Technologies Inc., Valencia, CA, USA) and controlled by a programmable driver (Intelligent Servo Drive IDM640-8EI, Technosoft, Canton, MI, USA). Lateral trunk displacement at the position of the adipose fin does not exceed 1.0 mm in C. aeneus [17]; these data were used to estimate a range of behaviourally relevant stimuli. A series of four randomly ordered step-and-hold stimuli (0.12, 0.24, 0.36 and 0.48 mm) of 5 s in duration were applied to the fin to assess the nerve's response to lateral deformation of the fin membrane.…”

Morphological development of Corydoras aff. paleatus (Siluriformes, Callichthyidae) and correlation with the emergence of motor and social behaviors

“…Fishes benefit from shoal membership through increased hydrodynamic efficiency, and augmented security and foraging success (Pitcher & Parrish, 1993). Some studies have devoted attention to development of behavior and sensory organs in Siluriformes (KhoDa et al, 1995;Pruzsinszky & laDich,1998;maguit et al, 2010;mukai et al, 2010;rahmah et al, 2011) but we believe this is the first study demonstrating developmental changes in aggregation size and in shoaling behavior in Corydoras aff. paleatus.…”