ZOO 2090 Lecture Notes - Lecture 9: Swim Bladder, Aortic Arches, Protopterus
Document Summary
Exchange surface between environment and respiratory organs. Need: large surface between environment medium and blood, thin barrier, effective ventilation. Large surface area, countercurrent exchange, thin water-to- blood barrier. Three types: pouched gills of lamprey (no gill covering, septal gills of shark (each individual septum protects each gill chamber, opercular gills of teleost. Reduction of number of gill bars and chambers. Loss of spiracle and loss of septa. Hagfish velum produces a current of water from the nostril to the gills. Lamprey tidal ventilation through compression/expansion of branchial cavity (mouth often attached to host) Active fish can use ram ventilation (mouth open while swimming) Buccal and opercular components act like a two- stroke pump with alternating cycles of negative and positive pressure. Lungs are paired structures ventral to the gut. Gas bladder is a single elongated sac dorsal to the gut used for buoyancy (swim bladder), but sometimes also help with respiration (respiratory gas bladder).
