A1.1.6 - Physical properties of water and the consequences for animals in aquatic habitats

Buoyancy

• How well an object can float

Buoyancy in Water

• Water = more dense

• Less energy needed to remain afloat

Buoyancy in Air

• Air = less dense

• More energy required to stay afloat

Viscosity

• Measure of a fluids resistance to flow, determined by the internal friction between its molecules

• High Viscosity = thicker, slower flowing liquid (like honey)

• Low Viscosity = thinner, faster flowing liquid (like water)

Viscosity in Water

• Water = more viscous

• Aquatic ‍organisms experience high drag forces while moving.

• Must overcome significant resistance to swim.

Viscosity in Air

• Air = low viscous

• Creates minimal resistance

Thermal Conductivity

• Rate at which heat transfers through a substance

Thermal Conductivity in Water

• Water = high thermal conductivity

• Conducts heat away from the body efficiently.

Thermal Conductivity in Air

• Air = Low Thermal Conductivity

• Poor conductor of heat

• Animals retain body heat more easily

Specific Heat Capacity

• Amount of energy required to raise the temperature of 1 gram of ‌a substance by 1°C

Specific Heat Capacity of Water

• Specific Heat Capacity = High

• Resists temperature changes

Specific Heat Capacity of Air

• Specific Heat Capacity = Low

• Air temperature changes rapidly with environmental conditions