Motility is the ability of an
organism
An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...
to move independently using
metabolic energy. This biological concept encompasses movement at various levels, from whole organisms to cells and subcellular components.
Motility is observed in animals, microorganisms, and even some plant structures, playing crucial roles in activities such as foraging, reproduction, and cellular functions. It is genetically determined but can be influenced by environmental factors.
In multicellular organisms, motility is facilitated by systems like the
nervous and
musculoskeletal
The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provid ...
systems, while at the cellular level, it involves mechanisms such as
amoeboid movement and
flagellar propulsion
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungus, fungal spores (zoospores), and from a wide range of microorganisms to provide Motility#Ce ...
. These cellular movements can be directed by external stimuli, a phenomenon known as taxis. Examples include
chemotaxis
Chemotaxis (from ''chemical substance, chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell organism, single-cell or multicellular organisms direct thei ...
(movement along chemical gradients) and
phototaxis
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive ...
(movement in response to light).
Motility also includes physiological processes like gastrointestinal movements and peristalsis. Understanding motility is important in biology, medicine, and ecology, as it impacts processes ranging from bacterial behavior to ecosystem dynamics.
Definitions
Motility, the ability of an
organism
An organism is any life, living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have be ...
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 means a lifeform that can be moved but only passively; 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, but may be affected by environmental factors such as
toxins
A toxin is a naturally occurring poison produced by metabolic activities of living cells or organisms. They occur especially as proteins, often conjugated. The term was first used by organic chemist Ludwig Brieger (1849–1919), derived ...
. The
nervous system
In biology, the nervous system is the complex system, highly complex part of an animal that coordinates its behavior, actions and sense, sensory information by transmitting action potential, signals to and from different parts of its body. Th ...
and musculoskeletal system provide the majority of mammalian motility.
In addition to
animal locomotion
In ethology, animal locomotion is any of a variety of methods that animals use to move from one place to another. Some modes of locomotion are (initially) self-propelled, e.g., running, swimming, jumping, flight, flying, hopping, soaring and gli ...
, most
animal
Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...
s are motile, though some are vagile, described as having
passive locomotion. Many
bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
and other
microorganism
A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...
s, including even some
viruses
A virus is a submicroscopic infectious agent that replicates only inside the living cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are found in almo ...
, and
multicellular organism
A multicellular organism is an organism that consists of more than one cell (biology), cell, unlike unicellular organisms. All species of animals, Embryophyte, land plants and most fungi are multicellular, as are many algae, whereas a few organism ...
s are motile; some mechanisms of
fluid flow
In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion ...
in multicellular organs and tissue are also considered instances of motility, as with
gastrointestinal motility
Gastrointestinal physiology is the branch of Human body, human physiology that addresses the physical function of the Human gastrointestinal tract, gastrointestinal (GI) tract. The function of the GI tract is to process ingested food by mechanical ...
. Motile
marine animal
Marine life, sea life or ocean life is the collective ecological communities that encompass all aquatic animals, aquatic plant, plants, algae, marine fungi, fungi, marine protists, protists, single-celled marine microorganisms, microorganisms ...
s are commonly called free-swimming, and motile non-
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...
organisms are called free-living.
Motility includes an organism's ability to move food through its
digestive tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...
. There are two types of intestinal motility –
peristalsis
Peristalsis ( , ) is a type of intestinal motility, characterized by symmetry in biology#Radial symmetry, radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an wikt:anterograde, anterograde dir ...
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 (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
Filopodia (: filopodium) are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells. Within the lamellipodium, actin ribs are known as ''microspikes'', and when they extend beyond the lamellipod ...
, enabling movement of the
axon
An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences) is a long, slender cellular extensions, projection of a nerve cell, or neuron, ...
al
growth cone
A growth cone is a large actin-supported extension of a developing or regenerating neurite seeking its synaptic target. It is the growth cone that drives axon growth. Their existence was originally proposed by Spanish histologist Santiago ...
*
flagellar motility
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores (zoospores), and from a wide range of microorganisms to provide motility. Many prot ...
, a swimming-like motion (observed for example in
spermatozoa
A spermatozoon (; also spelled spermatozoön; : spermatozoa; ) is a motile sperm cell (biology), cell produced by male animals relying on internal fertilization. A spermatozoon is a moving form of the ploidy, haploid cell (biology), cell that is ...
, propelled by the regular beat of their
flagellum
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...
, or the ''
E. coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus ''Escherichia'' that is commonly foun ...
'' bacterium, which swims by rotating a helical prokaryotic flagellum)
*
gliding motility
Gliding motility is a type of translocation used by microorganisms that is independent of propulsive structures such as flagella, pili, and fimbriae. Gliding allows microorganisms to travel along the surface of low aqueous films. The mechanisms ...
*
swarming motility
Swarming motility is a rapid (2–10 μm/s) and coordinated translocation of a bacterial population across solid or semi-solid surfaces, and is an example of bacterial multicellularity and swarm behaviour. Swarming motility was first reported by ...
*
twitching motility
Twitch may refer to:
Biology
* Muscle contraction
** Convulsion, rapid and repeated muscle contraction and relaxation
** Fasciculation, a small, local, involuntary muscle contraction
** Myoclonic twitch, a jerk usually caused by sudden muscle co ...
, a form of motility used by bacteria to crawl over surfaces using grappling hook-like filaments called
type IV pili.
Many cells are not motile, for example ''
Klebsiella pneumoniae
''Klebsiella pneumoniae'' is a Gram-negative, non-motile, encapsulated, lactose- fermenting, facultative anaerobic, rod-shaped bacterium. It appears as a mucoid lactose fermenter on MacConkey agar.
Although found in the normal flora of the mo ...
'' and ''
Shigella
''Shigella'' is a genus of bacteria that is Gram negative, facultatively anaerobic, non–spore-forming, nonmotile, rod shaped, and is genetically nested within ''Escherichia''. The genus is named after Kiyoshi Shiga, who discovered it in 1 ...
'', or under specific circumstances such as ''
Yersinia pestis
''Yersinia pestis'' (''Y. pestis''; formerly ''Pasteurella pestis'') is a Gram-negative bacteria, gram-negative, non-motile bacteria, non-motile, coccobacillus Bacteria, bacterium without Endospore, spores. It is related to pathogens ''Yer ...
'' at 37 °C.
Movements
Events perceived as movements can be directed:
* along a chemical gradient (see
chemotaxis
Chemotaxis (from ''chemical substance, chemo-'' + ''taxis'') is the movement of an organism or entity in response to a chemical stimulus. Somatic cells, bacteria, and other single-cell organism, single-cell or multicellular organisms direct thei ...
)
* along a temperature gradient (see
thermotaxis
Thermotaxis is a behavior in which an organism directs its locomotion up or down a gradient of temperature. Thermotaxis is a behavior that organisms navigate on depending on the temperature. ''“Thermo”'' means heat and or the temperature and ...
)
* along a light gradient (see
phototaxis
Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive ...
)
* along a magnetic field line (see
magnetotaxis
Magnetotaxis is a process implemented by a diverse group of Gram-negative bacteria that involves orienting and coordinating movement in response to Earth's magnetic field. This process is mainly carried out by microaerophilic and anaerobic bacter ...
)
* along an electric field (see
galvanotaxis)
* along the direction of the gravitational force (see
gravitaxis
Gravitaxis (or ''geotaxis'') is a form of taxis characterized by the directional movement of an organism in response to gravity.
There are a few different causes for gravitaxis. Many microorganisms have receptors like statocysts that allow them to ...
)
* along a rigidity gradient (see
durotaxis
In cellular biology, durotaxis is a form of cell migration in which Cell (biology), cells are guided by Stiffness, rigidity gradients, which arise from differential structural properties of the extracellular matrix (ECM). Most normal cells migrat ...
)
* along a gradient of cell adhesion sites (see
haptotaxis
In cellular biology, haptotaxis () is the directional motility or outgrowth of cells, e.g. in the case of axonal outgrowth, usually up a gradient of cellular adhesion sites or substrate-bound chemoattractants (the gradient of the chemoattractant b ...
)
* along other cells or
biopolymer
Biopolymers are natural polymers produced by the cells of living organisms. Like other polymers, biopolymers consist of monomeric units that are covalently bonded in chains to form larger molecules. There are three main classes of biopolymers, ...
s
File:Muscular system.svg, Muscles give the ability for voluntary movement, and involuntary movement as in muscle spasm
A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ, such as the bladder.
A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a musc ...
s and reflex
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus.
Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...
es. At the level of the muscular system
The muscular system is an organ (anatomy), organ system consisting of skeletal muscle, skeletal, smooth muscle, smooth, and cardiac muscle, cardiac muscle. It permits movement of the body, maintains posture, and circulates blood throughout the bo ...
, motility is a synonym for locomotion.
File:Sperm-20051108.jpg, Most sperm
Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...
have a single flagellum
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...
to help them swim. The cervical, uterine
The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic and fetal development of one or more fertilized eggs until bir ...
, and fallopian linings of the female reproductive system
The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are al ...
play a more important role in transporting sperm to ova
, abbreviated as OVA and sometimes as OAV (original animation video), are Japanese animated films and special episodes of a series made specially for release in home video formats without prior showings on television or in theaters, though the ...
.
File:Cheetah chase.jpg, The record speeds cheetahs hold are owed in large to their muscle motility.
File:Phototropism.jpg, The shoots of plants move by growing towards light. This is known as positive phototropism. The roots grow away from light. This is known as negative phototropism.
File:FAGOCITOSI BY RAFF.gif, Monocyte
Monocytes are a type of leukocyte or white blood cell. They are the largest type of leukocyte in blood and can differentiate into macrophages and monocyte-derived dendritic cells. As a part of the vertebrate innate immune system monocytes also ...
s and macrophage
Macrophages (; abbreviated MPhi, φ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that ...
s of the immune system
The immune system is a network of biological systems that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as Tumor immunology, cancer cells, Parasitic worm, parasitic ...
engulf Bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
by extending their pseudopodia
A pseudopod or pseudopodium (: pseudopods or pseudopodia) is a temporary arm-like projection of a eukaryotic cell membrane that is emerged in the direction of movement. Filled with cytoplasm, pseudopodia primarily consist of actin filaments and ...
. Note that this cartoon is not an accurate representation of phagocytosis
Phagocytosis () is the process by which a cell (biology), cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs ph ...
.
File:Protein translation.gif, Motility at the sub-cellular level. This depicts translation
Translation is the communication of the semantics, meaning of a #Source and target languages, source-language text by means of an Dynamic and formal equivalence, equivalent #Source and target languages, target-language text. The English la ...
- a motile nanoscale
Nanotechnology is the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm). At this scale, commonly known as the nanoscale, surface area and quantum mechanical effects become important in describing propertie ...
molecular process using protein dynamics
In molecular biology, proteins are generally thought to adopt unique structures determined by their amino acid sequences. However, proteins are not strictly static objects, but rather populate ensembles of (sometimes similar) conformations. Tran ...
.
See also
*
Cell migration
Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryogenesis, embryonic development, wound healing and immune system, immune responses all require the orchestrated movemen ...
References
{{Authority control
Physiology
Cell movement
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