Jumping or leaping is a form of locomotion or movement in which an organism propels itself through the air along a ballistic trajectory. Jumping can be distinguished from running, galloping and other gaits in which the entire body is temporarily airborne by the relatively long duration of the aerial phase and high angle of initial launch. Some animals, such as the kangaroo, use jumping, more commonly called hopping in this instance, as their primary form of locomotion, while others, such as frogs, use it only as a way to escape from predators.

Physics of jumping

A jump can be initiated when the animal is either moving or stationary. In a jump from stationary (a 'standing jump'), the animal is initially stationary, and all of the work done to accelerate the body through launch until takeoff is achieved is done in a single movement. The muscles do a certain amount of physical work (adding kinetic energy to the system), resulting in the final kinetic energy of the body (which is proportional to velocity squared). The more work the muscles do, the greater the final speed, thus the shorter the time interval of the jump's propulsive phase. Work divided by time = power. The more power generated, the greater the jump distance or height will be. Many jumping animals have muscles optimized for power production (as opposed to optimization for force or velocity), as well as adaptations such as elastic elements to increase power output.

In a moving jump or 'running jump', the animal simply redirects its velocity, attempting to conserve as much momentum as possible to add to the jump distance. Because the total kinetic energy of the jumping animal is not solely due to the jump movement itself, as is the case in a standing jump, but rather the energy of the jump plus the prior energy of the body, animals can often jump farther and higher if they 'get a running start'. In some cases, the animal will simply move in a give direction until they lose contact with it, without any specific launch movements, such as when a person runs across a gap from an elevated launch area, or when a dolphin swims upwards until breaking the surface at a given angle and velocity.

Jumping requires applying force against a substrate, which will in turn generate a reactive force, propelling the animal into the launch. This can be accomplished by pushing off against the ground or the water. In the latter case, dolphins often display moving jumps, while Indian skitter frogs can execute a standing jump from water. Jumping is typically defined by an airborne phase after launch from a substrate with a path defined by ballistic formulae, so animals cannot 'jump' underwater, as the drag and buoyancy overwhelm the influence of gravity. Similarly, while a bird can jump into the air in order to initiate flight, no movement it performs once airborne can be considered 'jumping'.