LocomotionEn physiologie, la locomotion est la faculté, pour un organisme vivant, de se mouvoir pour se déplacer. Des contraintes sont exercées sur ces organismes suivant le milieu, terrestre, aérien ou aquatique, dans lesquels ils se meuvent. La fonction locomotrice se traduit par un ensemble de mouvements qui entraînent le déplacement de l'être vivant : la progression quadrupède, bipède et apode, dont la reptation, en milieu terrestre, diverses formes de nage et de propulsion en milieu aquatique (système de propulsion par réaction des calmars) et les vols planés ou battus en milieu aérien.
Jet propulsionJet propulsion is the propulsion of an object in one direction, produced by ejecting a jet of fluid in the opposite direction. By Newton's third law, the moving body is propelled in the opposite direction to the jet. Reaction engines operating on the principle of jet propulsion include the jet engine used for aircraft propulsion, the pump-jet used for marine propulsion, and the rocket engine and plasma thruster used for spacecraft propulsion.
Bacterial motilityBacterial motility is the ability of bacteria to move independently using metabolic energy. Most motility mechanisms which evolved among bacteria also evolved in parallel among the archaea. Most rod-shaped bacteria can move using their own power, which allows colonization of new environments and discovery of new resources for survival. Bacterial movement depends not only on the characteristics of the medium, but also on the use of different appendages to propel. Swarming and swimming movements are both powered by rotating flagella.
Rotating locomotion in living systemsSeveral organisms are capable of rolling locomotion. However, true wheels and propellers—despite their utility in human vehicles—do not seem to play a significant role in the movement of living things (with the exception of certain flagella, which work like corkscrews). Biologists have offered several explanations for the apparent absence of biological wheels, and wheeled creatures have appeared often in speculative fiction.
Nageoirethumb|right|300px|Schéma d'un Téléostéen (majorité des poissons actuels, osseux à nageoires rayonnées), le Lampanyctodes hectoris1 opercule2 ligne latérale3 nageoire dorsale4 nageoire molle ou adipeuse5 pédoncule caudal ou queue6 nageoire caudale7 nageoire anale8 photophores9 nageoire ventrale ou pelvienne (par paire)10 nageoire pectorale (par paire). Une nageoire est un membre ou un appendice en général large et plat issu d'un repli cutané, permettant le mouvement et le soutien dans le milieu aquatique.
Terrestrial locomotionTerrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that in water, with reduced friction being replaced by the increased effects of gravity. As viewed from evolutionary taxonomy, there are three basic forms of animal locomotion in the terrestrial environment: legged – moving by using appendages limbless locomotion – moving without legs, primarily using the body itself as a propulsive structure.
Membre (anatomie)vignette|L'organisation modulaire des membres antérieurs (illustration) et postérieurs d'hominidés (chimpanzé, bonobo et homme) révèle une évolution en mosaïque avec certains caractères évolués et d'autres qui le sont moins. En anatomie, chez les animaux vertébrés, un membre est une partie du corps spécialisée dans la locomotion et sous-tendue par un squelette. Il existe deux grands types différents : les membres ptérygiens, ou nageoires, et les membres chiridiens, ou pentadactyles.
Undulatory locomotionUndulatory locomotion is the type of motion characterized by wave-like movement patterns that act to propel an animal forward. Examples of this type of gait include crawling in snakes, or swimming in the lamprey. Although this is typically the type of gait utilized by limbless animals, some creatures with limbs, such as the salamander, forgo use of their legs in certain environments and exhibit undulatory locomotion. In robotics this movement strategy is studied in order to create novel robotic devices capable of traversing a variety of environments.
Terrestrial animalTerrestrial animals are animals that live predominantly or entirely on land (e.g. cats, chickens, ants, spiders), as compared with aquatic animals, which live predominantly or entirely in the water (e.g. fish, lobsters, octopuses), and amphibians, which rely on a combination of aquatic and terrestrial habitats (e.g. frogs and newts). Some groups of insects are terrestrial, such as ants, butterflies, earwigs, cockroaches, grasshoppers and many others, while other groups are partially aquatic, such as mosquitoes and dragonflies, which pass their larval stages in water.
Webbed footThe webbed foot is a specialized limb with interdigital membranes (webbings) that aids in aquatic locomotion, present in a variety of tetrapod vertebrates. This adaptation is primarily found in semiaquatic species, and has convergently evolved many times across vertebrate taxa. It likely arose from mutations in developmental genes that normally cause tissue between the digits to apoptose. These mutations were beneficial to many semiaquatic animals because the increased surface area from the webbing allowed for more swimming propulsion and swimming efficiency, especially in surface swimmers.
