CVA.L10BB

The Aquatic Environment •

73% of of Earth’ Earth’s s surfac surface e is covere covered d by wate waterr, only only about about 0.01% 0.01% of this this water is contained in freshwater lakes, rivers, etc.  – However, However, freshwater systems are extremely rich biologically, biologically, and nearly 40% of all bony fishes live in freshwater 

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Water and air provide drastically different environments for vertebrates  – E.g., gravity is an important force acting on a terrestrial animal, but air resistance is trivial for all but the fastest birds  – In water, gravity is negligible, but fluid resistance to movement is a major factor