How can fishes occur in so many different aquatic environments?
(4) Life in water is a unifying feature of all fishes Properties of Water important to fish: A. Density (800 X air) provides structural support -Fishes neutrally buoyant, energy directed toward swimming -Water resists motion because of density and near incompressibility -Fishes usually streamlined to reduce resistance B. Nearly incompressable -used by fishes in lateral line system; can detect turbulance from displacement -suction feeding and respiration; create negative pressure forces water into buccal cavity, over gills C. Nearly Universal Solvent -water contains dissolved gases (like 02) and nutrients 1-8 ml of 02 per liter of water compared to 210 ml 02 per liter of air, efficient extraction requires highly specialized organ D. Low light penetration-light penetrates only to about 1000m “photic zone” portion of water column with enough light for photosynthesis (5) The History of Ichthyology This graphic could not be imported, sorry!
