Diurnality is a form of plant or animal behavior characterized by activity during daytime, with a period of sleeping or other inactivity at night. The common adjective used for daytime activity is "diurnal." The timing of activity by an animal depends on a variety of environmental factors such as the temperature, the ability to gather food by sight, the risk of predation, and the time of year. Diurnality is a cycle of activity within a 24-hour period; cyclic activities called circadian rhythms are endogenous cycles not dependent on external cues or environmental factors. Animals active during twilight are crepuscular, those active during the night are nocturnal, and animals active at sporadic times during both night and day are cathemeral.
Plants that open their flowers during the daytime are described as diurnal, while those that bloom during nighttime are nocturnal. The timing of flower opening is often related to the time at which preferred pollinators are foraging. For example, sunflowers open during the day to attract bees, whereas the night-blooming cereus opens at night to attract large sphinx moths.
Many types of animals are classified as being diurnal, meaning they are active during the day time and inactive or have periods of rest during the night time. Commonly classified diurnal animals include mammals, birds, and reptiles. Most primates are diurnal. Scientifically classifying diurnality within animals can be a challenge, apart from the obvious increased activity levels during the day time light.
Initially, most animals were diurnal, but adaptations that allowed some animals to become nocturnal is what helped contribute to the success of many, especially mammals. This evolutionary movement to nocturnality allowed them to better avoid predators and gain resources with less competition from other animals. This did come with some adaptations that mammals live with today. Vision has been one of the most greatly affected senses from switching back and forth from diurnality to nocturnality, and this can be seen using biological and physiological analysis of rod nuclei from primate eyes. This includes losing two of four cone opsins that assists in colour vision, making many mammals dichromats. When early primates converted back to diurnality, better vision that included trichromatic colour vision became very advantageous, making diurnality and colour vision adaptive traits of simiiformes, which includes humans. Studies using chromatin distribution analysis of rod nuclei from different simian eyes found that transitions between diurnality and nocturnality occurred several times within primate lineages, with switching to diurnality being the most common transitions.
Still today, diurnality seems to be reappearing in many lineages of other animals, including small rodent mammals like the Nile grass rat and golden mantle squirrel and reptiles. More specifically, geckos, which have thought to be naturally nocturnal have shown many transitions to diurnality, with about 430 species of geckos now showing diurnal activity. With so many diurnal species recorded, comparative analysis studies using newer lineages of gecko species have been done to study the evolution of diurnality. With about 20 transitions counted for the gecko lineages, it shows the significance of diurnality. Strong environmental influences like climate change, predation risk, and competition for resources are all contributing factors. Using the example of geckos, it is thought that species like Mediodactylus amictopholis that live at higher altitudes have switched to diurnality to help gain more heat through the day, and therefore conserve more energy, especially when colder seasonal temperatures hit.
Light is one of the most defining environmental factors that determines an animal’s activity pattern. Photoperiod or a light dark cycle is determined by the geographical location, with day time being associated with lots of ambient light, and night time being associated with little ambient light. Light is one of the strongest influences of the suprachiasmatic nucleus (SCN) which is part of the hypothalamus in the brain that controls the circadian rhythm in most animals. This is what determines whether an animal is diurnal or not. The SCN uses visual information like light to start a cascade of hormones that are released and work on many physiological and behavioural functions.
Light can produce powerful masking effects on an animal’s circadian rhythm, meaning that it can “mask” or influence the internal clock, changing the activity patterns of an animal, either temporarily or over the long term if exposed to enough light over a long period of time. Masking can be referred to either as positive masking or negative masking, with it either increasing an diurnal animals activity or decreasing a nocturnal animal's activity, respectively. This can be depicted when exposing different types of rodents to the same photoperiods. When a diurnal Nile grass rat and nocturnal mouse are exposed to the same photoperiod and light intensity, increased activity occurred within the grass rat (positive masking), and decreased activity within the mouse (negative masking).
Even small amounts of environmental light change have shown to have an effect on the activity of mammals. An observational study done on the activity of nocturnal owl monkeys in the Gran Chaco in South America showed that increased amounts of moonlight at night increased their activity levels through the night, which led to a decrease of daytime activity. Meaning that for this species, ambient moonlight is negatively correlated with diurnal activity. This is also connected with the foraging behaviours of the monkeys, as when there were nights of little to no moonlight, it affected the monkey’s ability to forage efficiently, so they were forced to be more active in the day to find food.
Diurnality has shown to be an evolutionary trait in many animal species, with diurnality mostly reappearing in many lineages. Other environmental factors like ambient temperature, food availability, and predation risk can all influence whether an animal will evolve to be diurnal, or if their effects are strong enough, then mask over their circadian rhythm, changing their activity patterns to becoming diurnal. All three factors often involve one another, and animals need to be able to find a balance between them if they are to survive and thrive.
Ambient temperature has been shown to affect and even convert nocturnal animals to diurnality as it is a way for them to conserve metabolic energy. Nocturnal animals are often energetically challenged due to being most active in the nighttime when ambient temperatures are lower than through the day, and so they lose a lot of energy in the form of body heat. According to the circadian thermos-energetics (CTE) hypothesis, animals that are expending more energy than they are taking in (through food and sleep) will be more active in the light cycle, meaning they will be more active in the day. This has been shown in studies done on small nocturnal mice in a laboratory setting. When they were placed under a combination of enough cold and hunger stress, they converted to diurnality through temporal niche switching, which was expected. Another similar study that involved energetically challenging small mammals showed that diurnality is most beneficial when the animal has a sheltered location to rest in, reducing heat loss. Both studies concluded that nocturnal mammals do change their activity patterns to be more diurnal when energetically stressed (due to heat loss and limited food availability), but only when predation is also limited, meaning the risks of predation are less than the risk of freezing or starving to death.
Many plants are diurnal or nocturnal, depending on the time period when the most effective pollinators, i.e., insects, visit the plant. Most angiosperm plants are visited by various insects, so the flower adapts its phenology to the most effective pollinators. Thus, the effectiveness of relative diurnal or nocturnal species of insects affects the diurnal or nocturnal nature of the plants they pollinate, causing in some instances an adjustment of the opening and closing cycles of the plants. For example, the baobab is pollinated by fruit bats and starts blooming in late afternoon; the flowers are dead within twenty-four hours.
Services that alternate between high and low utilization in a daily cycle are described as being diurnal. Many websites have the most users during the day and little utilization at night, or vice versa. Operations planners can use this cycle to plan, for example, maintenance that needs to be done when there are fewer users on the web site.
The Andean hairy armadillo (Chaetophractus nationi) is an armadillo located in Bolivia, in the region of the Puna; the departments of Oruro, La Paz, and Cochabamba (Gardner, 1993). Nowark (1991) describes it as distributed in Bolivia and northern Chile. A recent publication of Pacheco (1995) also locates the species in Peru, basically in Puno Region. This species is also thought to be present in northern Argentina. However, this location may actually only contain a population of C. vellerosus.Brush-furred mouse
The brush-furred mice, genus Lophuromys are a group of rodents found in sub-Saharan Africa. They are members of the subfamily Deomyinae, a group only identifiable through molecular analysis. Lophuromys is also known as the brush-furred rats, harsh-furred rats or coarse-haired mice.Cathemerality
Cathemerality, sometimes called metaturnality, is the behaviour in which an organism has sporadic and random intervals of activity during the day or night in which food is acquired, socializing with other organisms occurs, and any other activities necessary for livelihood are performed. It has been defined as follows: "The activity of an organism may be regarded as cathemeral when it is distributed approximately evenly throughout the 24 h of the daily cycle, or when significant amounts of activity, particularly feeding and/or traveling, occur within both the light and dark portions of that cycle."Many animals do not fit the traditional definitions of being strictly nocturnal, diurnal, or crepuscular, often by factors that include the availability of food, predation pressure, and variable ambient temperature. As a result, many species, particularly among primates, may be classified as cathemeral.Alternative patterns of cathemeral activity have been observed in specific lemurs. Seasonal cathemerality has been described for the mongoose lemur (Eulemur mongoz) as activity that shifts from being predominantly diurnal to being predominantly nocturnal over a yearly cycle. The Common brown lemurs (E. fulvus fulvus) have been observed as seasonally shifting from diurnal activity to cathemerality.Chronobiology
Chronobiology is a field of biology that examines periodic (cyclic) phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms. Chronobiology comes from the ancient Greek χρόνος (chrónos, meaning "time"), and biology, which pertains to the study, or science, of life. The related terms chronomics and chronome have been used in some cases to describe either the molecular mechanisms involved in chronobiological phenomena or the more quantitative aspects of chronobiology, particularly where comparison of cycles between organisms is required.
Chronobiological studies include but are not limited to comparative anatomy, physiology, genetics, molecular biology and behavior of organisms within biological rhythms mechanics. Other aspects include epigenetics, development, reproduction, ecology and evolution.Crepuscular animal
Crepuscular animals are those that are active primarily during twilight (that is, the periods of dawn and dusk). This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylight or the hours of darkness, respectively. The term is not precise, however, as some crepuscular animals may also be active on a moonlit night or during an overcast day. The term matutinal is used for animals that are active only before sunrise, and vespertine for those active only after sunset.
The time of day an animal is active depends on a number of factors. Predators need to link their activities to times of day at which their prey is available, and prey try to avoid the times when their principal predators are at large. The temperature at midday may be too high or at night too low. Some creatures may adjust their activities depending on local competition. Therefore, for many varied reasons, crepuscular activity may best meet an animal's requirements by compromise.Diel (disambiguation)
Diel is a pattern of movement used by some organisms living in the ocean and in lakes.Diurnal cycle
A diurnal cycle is any pattern that recurs every 24 hours as a result of one full rotation of the Earth around its own axis.
In climatology, the diurnal cycle is one of the most basic forms of climate patterns. The most familiar such pattern is the diurnal temperature variation. Such a cycle may be approximately sinusoidal, or include components of a truncated sinusoid (due to the sun's rising and setting) and thermal relaxation (Newton cooling) at night.
Diurnal cycles of environmental conditions (light or temperature) can result in similar cycles in dependent biological processes, such as photosynthesis in plants, or clinical depression in humans. Plant responses to environmental cycles may even induce indirect cycles in rhizosphere microbial activities, including nitrogen fixation.A semi-diurnal cycle refers to a pattern that occurs about every twelve hours or about twice a day. Often these can be related to lunar tides, in which case the interval is closer to 12 hours and 25 minutes.Everyday life
Everyday life, daily life or routine life comprises the ways in which people typically act, think, and feel on a daily basis. Everyday life may be described as mundane, routine, natural, habitual, or normal.
Human diurnality means most people sleep at least part of the night and are active in daytime. Most eat two or three meals in a day. Working time (apart from shift work) mostly involves a daily schedule, beginning in the morning. This produces the daily rush hours experienced by many millions, and the drive time focused on by radio broadcasters. Evening is often leisure time. Bathing every day is a custom for many.
Beyond these broad similarities, lifestyles vary and different people spend their days differently. Nomadic life differs from sedentism, and among the sedentary, urban people live differently from rural folk. Differences in the lives of the rich and the poor, or between factory workers and intellectuals, may go beyond their working hours. Many women spend their day in activities greatly different from those of men, and everywhere children do different things than adults.Lark (person)
A lark, early bird, morning person or, in Scandinavian countries, an A-person, is a person who usually gets up early in the morning and goes to bed early in the evening. The lark (bird) starts its day very early, which explains the choice of the word lark for people who may sleep from around 10 p.m. to 6 a.m. or earlier. Human "larks" tend to feel most energetic just after they get up in the morning. They are thus well-suited for working the day shift.
The opposite of the lark is the owl, often awake at night. A person called a night owl is someone who usually stays up late and may feel most awake in the evening and at night. Researchers have traditionally used the terms morningness and eveningness to describe these two phenotypes.List of nocturnal animals
This is a list of nocturnal alligator and groups of animals. Birds are listed separately in the List of nocturnal birds.List of nocturnal birds
There are many birds that are active nocturnally. Some, like owls and nighthawks, are predominantly nocturnal whereas others do specific tasks, like migrating, nocturnally.
North Island brown kiwi, Apteryx mantelli
Barn owl, Tyto alba
Short-eared owl, Asio flammeus
Long-eared owl, Asio otus
Great horned owl, Bubo virginianus
Barred owl, Strix varia
Spotted owl, Strix occidentalis
Eastern screech-owl, Megascops asio
Western screech-owl, Megascops kennicottii
Whiskered screech-owl, Megascops trichopsis
Flammulated owl, Psiloscops flammeolus
Elf owl, Micrathene whitneyi
Great gray owl, Strix nebulosa
Northern saw-whet owl, Aegolius acadicus
Boreal owl, Aegolius funereus
Burrowing owl, Athene cunicularia
Kakapo, Strigops HabroptilaLizard
Lizards are a widespread group of squamate reptiles, with over 6,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes and Amphisbaenia; some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3 meter long Komodo dragon.
Most lizards are quadrupedal, running with a strong side-to-side motion. Others are legless, and have long snake-like bodies. Some such as the forest-dwelling Draco lizards are able to glide. They are often territorial, the males fighting off other males and signalling, often with brightly colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators; many smaller species eat insects, while the Komodo eats mammals as big as water buffalo.
Lizards make use of a variety of antipredator adaptations, including venom, camouflage, reflex bleeding, and the ability to sacrifice and regrow their tails.Night owl (person)
A night owl, evening person or simply owl, is a person who tends to stay up until late at night, or the early hours of the morning. In several countries, especially in Scandinavia, early birds are called A-people and night owls are called B-people. Night owls who are involuntarily unable to fall asleep for several hours after a normal time may have delayed sleep phase syndrome.
The opposite of a night owl is an early bird – a lark as opposed to an owl – which is someone who tends to begin sleeping at a time that is considered early and also wakes early. Researchers traditionally use the terms morningness and eveningness for the two chronotypes or diurnality and nocturnality in animal behavior.Nocturnality
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed senses of hearing, smell, and specially adapted eyesight. Such traits can help animals such as the Helicoverpa zea moths avoid predators. Some animals, such as cats and ferrets, have eyes that can adapt to both low-level and bright day levels of illumination (see metaturnal). Others, such as bushbabies and (some) bats, can function only at night. Many nocturnal creatures including tarsiers and some owls have large eyes in comparison with their body size to compensate for the lower light levels at night. More specifically, they have been found to have a larger cornea relative to their eye size than diurnal creatures to increase their visual sensitivity: in the low-light conditions. Nocturnality helps wasps, such as Apoica flavissima, avoid hunting in intense sunlight.
Diurnal animals, including squirrels and songbirds, are active during the daytime. Crepuscular species, such as rabbits, skunks, tigers, and hyenas, are often erroneously referred to as nocturnal. Cathemeral species, such as fossas and lions, are active both in the day and at night.
While most humans are diurnal, for various personal and social/cultural reasons some people are temporarily or habitually nocturnal.
The most known creatures to be nocturnal include cats, rodents, and owls, which all have heightened senses (including their sense of sight).Squirrel
Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels, chipmunks, marmots (including woodchucks), flying squirrels, and prairie dogs amongst other rodents. Squirrels are indigenous to the Americas, Eurasia, and Africa, and were introduced by humans to Australia. The earliest known squirrels date from the Eocene period and are most closely related to the mountain beaver and to the dormouse among other living rodent families.Stemflow
In hydrology, stemflow is the flow of intercepted water down the trunk or stem of a plant. Stemflow, along with throughfall, is responsible for the transferral of precipitation and nutrients from the canopy to the soil. In tropical rainforests, where this kind of flow can be substantial, erosion gullies can form at the base of the trunk. However, in more temperate climates stemflow levels are low and have little erosional power.Tornado climatology
Tornadoes have been recorded on all continents except Antarctica and are most common in the middle latitudes where conditions are often favorable for convective storm development. The United States has the most tornadoes of any country, as well as the strongest and most violent tornadoes. A large portion of these tornadoes form in an area of the central United States popularly known as Tornado Alley. Other areas of the world that have frequent tornadoes include significant portions of Europe, South Africa, Philippines, Bangladesh, parts of Argentina, Uruguay, and southern and southeast Brazil, northern Mexico, New Zealand, and far eastern Asia.The United States averaged 1,274 tornadoes per year in the last decade while Canada reports nearly 100 annually (largely in the southern regions). However, the UK has most tornadoes per area per year, 0.14 per 1000 km², although these tornadoes are generally weak, and many other European countries have a similar number of tornadoes per area.The severity of tornadoes is commonly measured by the Enhanced Fujita Scale, which scales tornado intensity from EF0 to EF5 by wind speed and the amount of damage they do to human environments. These judgments are made after the tornado has dissipated and the damage trail is carefully studied by weather professionals.Tornadoes are most common in spring and least common in winter. The seasonal transition during autumn and spring promotes the development of extratropical cyclones and frontal systems that support strong convective storms. Tornadoes are also common in landfalling tropical cyclones, where they are focused in the right poleward section of the cyclone. Tornadoes can also be spawned as a result of eyewall mesovortices, which persist until landfall. However, favorable conditions for tornado development can occur any time of the year.
Tornado occurrence is highly dependent on the time of day, because of solar heating. Worldwide, most tornadoes occur in the late afternoon, between 3 pm and 7 pm local time, with a peak near 5 pm. Destructive tornadoes can occur at any time of day, as evidenced by the Gainesville Tornado of 1936 (one of the deadliest tornadoes in history) that occurred at 8:30 am local time.Unstriped ground squirrel
The unstriped ground squirrel (Xerus rutilus) is a species of rodent (order Rodentia) in the family Sciuridae. It is found in Djibouti, Eritrea, Ethiopia, Kenya, Somalia, Sudan, Tanzania, and Uganda. Its natural habitats are dry savanna and subtropical or tropical dry shrubland.