There are probably differences in the cost of breathing among fish.
Fish, like carp and tench, in still water, must pump water over their
gills. These fish probably have the highest cost of ventilation, and so
they tend to have low ventilation volumes (ventilation volume is the
volume of water passing over the gills per unit of time ) and high percent
utilization of oxygen in the water (Garey, 1967; Baumgarten and Randall,
1967 ). Fish swimming rapidly or fish that can maintain position in fast
Bowing water need only open their mouths to ventilate their gills.
Gill ventilation in this case is related to swimming speed, water Bow
rate, resistance to water Bow through the gills, and the gape of the mouth
and operculum (Muir and Kendall, 1968 ). At high swimming speeds
the problem may be to reduce water Bow over the gills rather than main
tain an adequate rate of ventilation. In these fish the cost of ventilating
the gills is probably small and related to the increased resistance to
forward motion produced by passing water over the gills. Salmonids
can maintain position in fast Bowing water using only fr ictional forces
between the fish and the bottom. As water Bow is increased the amplitude
of breathing decreases; residual breathing movements are always present,
đang được dịch, vui lòng đợi..
