Life in A Fluid Medium

Density

Measure of how much mass there is in a given volume

Buoyancy

Determined by the density of an object relative to the density of the fluid it is in. Determines if an object will float, sink, or be neutrally buoyant.

Viscosity

Measure of the resistance of a fluid to flow. The less viscous a fluid is, the greater its ease of movement.

Laminar Flow

Smooth, orderly flow of a fluid. Occurs at low speeds and in small diameter tubes.

Turbulent Flow

Chaotic, irregular flow of a fluid. Occurs at high speeds and in large diameter tubes.

Reynold's Number

Dimensionless ratio of inertial forces to viscous forces. Determines if flow is laminar or turbulent.

Principle of Continuity

Mass is always conserved in a fluid system regardless of pipeline complexity or direction of flow.

Water Flow in Sponges

Water flows through sponges in one direction, driven by the beating of flagella of specialized cells called choanocytes.

Bernoulli's Principle

Higher pressure regions have lower fluid speed and lower pressure regions have higher fluid speed.

Drag

Force exerted by a fluid stream on any obstacle in its path or felt by an object moving through a fluid.

Boundary Layers

Thin layer of low energy flow generated along a solid surface in contact with a fluid.

Schooling

Organized formations of aquatic animals that reduce drag and enhance locomotion performance.

Maneuverability

Ability of a swimming animal to change direction and perform complex movements.