Dormancy is a period in an organism's
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...

 life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...

 when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 and therefore helps an organism to conserve energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

. Dormancy tends to be closely associated with environmental conditions
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

. Organisms can synchronize entry to a dormant phase with their environment
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....

 through predictive or consequential means. Predictive dormancy occurs when an organism enters a dormant phase before the onset of adverse conditions. For example, photoperiod and decreasing temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...

 are used by many plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s to predict the onset of winter. Consequential dormancy occurs when organisms enter a dormant phase after adverse conditions have arisen. This is commonly found in areas with an unpredictable climate. While very sudden changes in conditions may lead to a high mortality rate
Mortality rate
Mortality rate is a measure of the number of deaths in a population, scaled to the size of that population, per unit time...

 among animals relying on consequential dormancy, its use can be advantageous, as organisms remain active longer and are therefore able to make greater use of available resources.


Hibernation is a mechanism used by many animals to escape cold weather and food shortage over the winter. Hibernation may be predictive or consequential. An animal prepares for hibernation by building up a thick layer of body fat during late summer and autumn that will provide it with energy during the dormant period. During hibernation, the animal undergoes many physiological
Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

 changes, including decreased heart rate
Heart rate
Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....

 (by as much as 95%) and decreased body temperature. Animals that hibernate include bats, ground squirrel
Ground squirrel
The ground squirrels are members of the squirrel family of rodents which generally live on or in the ground, rather than trees. The term is most often used for the medium-sized ground squirrels, as the larger ones are more commonly known as marmots or prairie dogs, while the smaller and less...

s and other rodents, mouse lemurs, the European Hedgehog
European Hedgehog
The European Hedgehog , Common hedgehog or just Hedgehog in the anglophone parts of Europe, is a hedgehog species found in northern and western Europe. It is about 20 to 30 cm in length. Adult mass typically ranges from 600 to up to 1,200 g ; occasionally, it may reach as much as...

 and other insectivores, monotremes and marsupials.


Diapause is a predictive strategy that is predetermined by an animal's genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...

. Diapause is common in insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s, allowing them to suspend development between autumn and spring, and in mammals such as the roe deer (Capreolus capreolus, the only ungulate with embryonal diapause), where a delay in attachment of the embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

 to the uterine
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

 lining ensures that offspring
In biology, offspring is the product of reproduction, of a new organism produced by one or more parents.Collective offspring may be known as a brood or progeny in a more general way...

 are born in spring, when conditions are most favorable.


Aestivation, also spelled estivation, is an example of consequential dormancy in response to very hot or dry conditions. It is common in invertebrates such as the garden snail
Helix (genus)
Helix is a genus of large air-breathing land snails, terrestrial pulmonate gastropod molluscs. This genus is native to Europe and the regions around the Mediterranean Sea. Helix is the type genus of the family Helicidae....

 and worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...

 but also occurs in other animals such as the lungfish
Lungfish are freshwater fish belonging to the Subclass Dipnoi. Lungfish are best known for retaining characteristics primitive within the Osteichthyes, including the ability to breathe air, and structures primitive within Sarcopterygii, including the presence of lobed fins with a well-developed...



Dormancy in reptiles is an example of brumation, which is similar to hibernation
Hibernation is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernating animals conserve food, especially during winter when food supplies are limited, tapping energy reserves, body fat, at a slow rate...

. It differs from hibernation in the metabolic processes involved.

Reptiles generally begin brumation in late fall (more specific times depend on the species). They will often wake up to drink water and return to "sleep". They can go months without food. Reptiles may want to eat more than usual before the brumation time but will eat less or refuse food as the temperature drops. However, they do need to drink water. The brumation period is anywhere from one to eight months depending on the air temperature and the size, age, and health of the reptile. During the first year of life, many small reptiles do not fully brumate, but rather slow down and eat less often. Brumation should not be confused with hibernation; when mammals hibernate, they are actually asleep; when reptiles brumate, they are less active, and their metabolism slows down so they just do not need to eat as often. Reptiles can often go through the whole winter without eating. Brumation is triggered by cold weather, lack of heat, and the decrease in the amount of hours of daylight in the winter.


A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es of the family Herpesvirus are notable for remaining dormant within cells
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

 in the human body. See, for example, varicella zoster virus
Varicella zoster virus
Varicella zoster virus is one of eight herpes viruses known to infect humans . It commonly causes chicken-pox in children and Herpes zoster in adults and rarely in children.-Nomenclature:...

, which in an individual causes first chickenpox
Chickenpox or chicken pox is a highly contagious illness caused by primary infection with varicella zoster virus . It usually starts with vesicular skin rash mainly on the body and head rather than at the periphery and becomes itchy, raw pockmarks, which mostly heal without scarring...

, then shingles (herpes zoster
Herpes zoster
Herpes zoster , commonly known as shingles and also known as zona, is a viral disease characterized by a painful skin rash with blisters in a limited area on one side of the body, often in a stripe...

). Concerning viruses, this dormancy is often referred to as latency or a latent infection. HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...

 produces a latent infection in lymphocytes, and, at this stage in its life-cycle, it is called a provirus
A provirus is a virus genome that is integrated into the DNA of a host cell.This state can be a stage of virus replication, or a state that persists over longer periods of time as either inactive viral infections or an endogenous retrovirus. In inactive viral infections the virus will not replicate...


This should not be confused with clinical latency.


In plant physiology
Plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...

, dormancy is a period of arrested plant growth. It is a survival strategy exhibited by many plant species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, which enables them to survive in climate
Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

s where part of the year is unsuitable for growth, such as winter or dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...


Many plant species that exhibit dormancy have a biological clock
Circadian rhythm
A circadian rhythm, popularly referred to as body clock, is an endogenously driven , roughly 24-hour cycle in biochemical, physiological, or behavioural processes. Circadian rhythms have been widely observed in plants, animals, fungi and cyanobacteria...

 that tells them when to slow activity and to prepare soft tissues for a period of freezing temperatures or water shortage. On the other hand, dormancy can be triggered after a normal growing season by decreasing temperatures, shortened day length, and/or a reduction in rainfall. The images below show two particularly widespread dormancy patterns amongst sympodial
Sympodial means "with conjoined feet", and in biology is often used to refer to the outward morphology or mode of growth of organisms.-In botany:...

ly growing orchids:


When a mature seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

 is placed under favorable conditions and fails to germinate, it is said to be dormant. Seed dormancy
Seed dormancy
Seed dormancy is a condition of plant seeds that prevents germination when the seeds are under optimal environmental conditions for germination. Living, non dormant seeds germinate when soil temperatures and moisture conditions are suited for cellular processes and division; dormant seeds do...

 is referred to as embryo dormancy or internal dormancy and is caused by endogenous characteristics of the embryo that prevent germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

 (Black M, Butler J, Hughes M. 1987). The oldest seed that has been germinated into a viable plant was an approximately 1,300-year-old lotus
Nelumbo nucifera
Nelumbo nucifera, known by a number of names including Indian Lotus, Sacred Lotus, Bean of India, or simply Lotus, is a plant in the monogeneric family Nelumbonaceae...

 fruit recovered from a dry lakebed in northeastern China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. Dormancy should not be confused with seed coat dormancy, external dormancy, or hardseededness, which is caused by the presence of a hard seed covering or seed coat that prevents water and oxygen from reaching and activating the embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...

. It is a physical barrier to germination, not a true form of dormancy (Quinliven, 1971; Quinliven and Nichol, 1971).


Tree species that have well-developed dormancy needs may be tricked to some degree, but not completely. For instance, if a Japanese Maple (Acer palmatum) is given an "eternal summer" through exposure to additional daylight, it will grow continuously for as long as two years. Eventually, however, a temperate climate plant will automatically go dormant, no matter what environmental conditions it experiences. Deciduous
Deciduous means "falling off at maturity" or "tending to fall off", and is typically used in reference to trees or shrubs that lose their leaves seasonally, and to the shedding of other plant structures such as petals after flowering or fruit when ripe...

 plants will lose their leaves; evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...

s will curtail all new growth. Going through an "eternal summer" and the resultant automatic dormancy is stressful to the plant and usually fatal. The fatality rate increases to 100% if the plant does not receive the necessary period of cold temperatures required to break the dormancy. Most plants will require a certain number of hours of "chilling" at temperatures between about 0°C and 10°C to be able to break dormancy (Bewley, Black, 1994).


Many bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 can survive adverse conditions such as temperature, desiccation
Desiccation is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic substance that induces or sustains such a state in its local vicinity in a moderately sealed container.-Science:...

, and antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...

s by endospore
An endospore is a dormant, tough, and temporarily non-reproductive structure produced by certain bacteria from the Firmicute phylum. The name "endospore" is suggestive of a spore or seed-like form , but it is not a true spore . It is a stripped-down, dormant form to which the bacterium can reduce...

s, cyst
A cyst is a closed sac, having a distinct membrane and division on the nearby tissue. It may contain air, fluids, or semi-solid material. A collection of pus is called an abscess, not a cyst. Once formed, a cyst could go away on its own or may have to be removed through surgery.- Locations :* Acne...

s, conidia or states of reduced metabolic activity lacking specialized cellular structures. Up to 80% of the bacteria in samples from the wild appear to be metabolically inactive—many of which can be resuscitated. Such dormancy is responsible for the high diversity levels of most natural ecosystems.
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