ZOOL 403 Lecture 16: Osteichthyes 1
9 May 2020
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Almost all vertebrates are osteichthyans: bony fishes are most, we evolved from bony fishes, tetrapods as well. Water vs air: density: 833x more dense, oxygen content: 32x less/volume, viscosity: 50x more viscous. Web- viscosity is the resistance to flow: refractive index:0. 33x greater, thermal capacity: 3333x greater (have to spend more energy to increase temp in water), velocity of sound: 4. 3x greater, surface tension: n/a, oxygen solubility: n/a, co2 solubility: n/a. Consequences: density: effects of gravity lessened because water is more dense than air, viscosity: resistance; shape, surface structure, gas exchange; pumping. Fishes have certain shape to minimize resistance, significant energy is required to pump in order to exchange gases: oxygen content: ventilation not tidal, thermal capacity: faster conduction of heat. Thermal challenges (example, get cold quicker), if you"re wet becomes cold quiker: electrical conductivity: can use electricity as a sensory modality for predation and communication, pressure increases as you go more down in water.
