Motility is the ability of an
organism to move independently, using metabolic energy.
Definitions
Motility, the ability of an
organism to move independently, using metabolic energy,
can be contrasted with
sessility, the state of organisms that do not possess a means of self-locomotion and are normally immobile.
Motility differs from mobility, the ability of an object to be moved.
The term vagility encompasses both motility and mobility; sessile organisms including plants and fungi often have vagile parts such as fruits, seeds, or spores which may be dispersed by other agents such as wind, water, or other organisms.
Motility is
genetically determined
Biological determinism, also known as genetic determinism, is the belief that human behaviour is directly controlled by an individual's genes or some component of their physiology, generally at the expense of the role of the environment, whether ...
, but may be affected by environmental factors such as toxins. The nervous system and musculoskeletal system provide the majority of mammalian motility.
In addition to animal locomotion, most animals are motile, though some are vagile, described as having Animal locomotion#Passive locomotion, passive locomotion. Many bacteria and other microorganisms, and multicellular organisms are motile; some mechanisms of fluid flow in multicellular organs and tissue are also considered instances of motility, as with Gastrointestinal physiology#Motility, gastrointestinal motility. Motile marine animals are commonly called free-swimming, and motile non-parasitic organisms are called free-living.
Motility includes an organism's ability to move food through its gastrointestinal tract, digestive tract. There are two types of intestinal motility – peristalsis and segmentation contractions, segmentation. This motility is brought about by the contraction of smooth muscles in the gastrointestinal tract which mix the luminal contents with various secretions (segmentation) and move contents through the digestive tract from the mouth to the anus (peristalsis).
Cellular level
At the cellular level, different modes of movement exist:
* amoeboid movement, a crawling-like movement, which also makes swimming possible
* filopodia, enabling movement of the axonal growth cone
* flagellar motility, a swimming-like motion (observed for example in spermatozoa, propelled by the regular beat of their flagellum, or the ''E. coli'' bacterium, which swims by rotating a helical prokaryotic flagellum)
* gliding motility
* swarming motility
* twitching motility, a form of motility used by bacteria to crawl over surfaces using grappling hook-like filaments called Pilus#Type IV pili, type IV pili.
Many cells are not motile, for example ''Klebsiella pneumoniae'' and ''Shigella'', or under specific circumstances such as ''Yersinia pestis'' at 37 °C.
Movements
Events perceived as movements can be directed:
* along a chemical gradient (see chemotaxis)
* along a temperature gradient (see thermotaxis)
* along a light gradient (see phototaxis)
* along a magnetic field line (see magnetotaxis)
* along an electric field (see galvanotaxis)
* along the direction of the gravitational force (see gravitaxis)
* along a rigidity gradient (see durotaxis)
* along a gradient of cell adhesion sites (see haptotaxis)
* along other cells or biopolymers
File:Muscular system.svg, Muscles give the ability for voluntary movement, and involuntary movement as in muscle spasms and reflexes). At the level of the muscular system, motility is a synonym for Animal locomotion, locomotion.
See also
* Cell migration
References
{{Authority control
Physiology
Cell movement
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