Comparative Vertebrate Physiology

Locomotion

Energetics: What does it cost? Smaller animals show higher rates of limb stride or wing

motion, thus higher rate of muscle shortening in smaller animals, thus more energy

Energetics Larger animals expend less energy

moving a given distance

How do animals move?Terrestrial locomotion1. Walking and running

Fewer points of contact with substrate than number of limbsMaintain equilibrium

How do animals move? 1. Walking and running

Gait Relative phase and duty factor Duty factor decreases with speed

How do animals move? 2. Hopping and jumping

Legs in phase Low duty factor when moving Low metabolic expenditure

Achilles tendon

Factors effecting locomotion Inertia Momentum Drag: determined by velocity, surface area and shape of an

animal Larger animals experience less drag

Drag

Experienced by swimmers (high viscosity and density) and fliers (velocity), but not runners

Aquatic energetics Swimming at the water surface is more

expensive

Aerial locomotion

No buoyancy Low drag Lift enables high speed travel Gliding conserves energy

Aerial locomotion Large animals generate more forward

thrust Differing angles of wing beat among fliers

Cost of transport

• Smaller animals havehigh cost of transportation

• At the same mass swimmingis most efficient

• Flying is more economicalthan running