Motility


Motility is the ability of an organism to move independently, using metabolic energy. This is in contrast to mobility, which describes the ability of an object to be moved. Motility is genetically determined, but may be affected by environmental factors. For instance, muscles give animals motility but the consumption of hydrogen cyanide would adversely affect muscle physiology, causing them to stiffen, leading to rigor mortis. In addition to animal locomotion, most animals are motile. The term applies to bacteria and other microorganisms, and to some multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs and tissue. Motile marine animals are commonly called free-swimming, and motile non-parasitic organisms are called free-living.
Motility also refers to an organism's ability to move food through its digestive tract. There are two types of intestinal motility – peristalsis and segmentation. This motility is brought about by the contraction of smooth muscles in the gastrointestinal tract which mix the luminal contents with various secretions and move contents through the digestive tract from the mouth to the anus.

Cellular-level motility

At the cellular level, different modes of motility exist:
Many cells are not motile, for example Klebsiella pneumoniae and Shigella, or under specific circumstances such as Yersinia pestis at 37 °C.

Muscle contraction

The nervous system and musculoskeletal system control the majority of mammalian motility. Gastrointestinal motility is essential for digestion.

Movements

The events that are perceived as movements can be directed: