Aestivation

From Wikipedia, the free encyclopedia

(Redirected from Estivation)

Aestivation (from Latin aestas, summer, but also spelled "estivation" in the USA)

is a state of animal dormancy,

^[1] characterized by inactivity and a lowered metabolic rate,

that is entered in response to high temperatures

and arid conditions.^[2] It takes place during times of heat and dryness,

the hot dry season, which is often

but not necessarily the summer months.^{[citation needed]}

Invertebrate and vertebrate animals are known to enter this state

to avoid damage from high temperatures and

the risk of desiccation. Both terrestrial and aquatic

animals undergo aestivation.^{[citation needed]}

Torpor

From Wikipedia, the free encyclopediarely upon torpor to survive.

Look up torpor in Wiktionary, the free dictionary.

Torpor, sometimes called temporary hibernation^[1] is a (usually short-term)

state of decreased

physiological activity in an animal, usually characterized by a reduced

body temperature and rate

of metabolism. Animals that go through torpor include birds

(even tiny hummingbirds, notably

Cypselomorphae) and some mammals such as mice and bats.^[2^]

During the active part of their day,

animals that undergo daily torpor maintain normal body

temperature and activity levels, but their

temperature drops during a portion of the day (usually night)

to conserve energy. Torpor is often

used to help animals survive during periods of colder temperatures,

as it allows the organism to save

the amount of energy that would normally

be used to maintain a high body temperature.

Torpor may extend for a longer period of time.

Some animals such as groundhogs, ground squirrels

and jumping mice enter this intensely deep state

of hibernation for the duration of the winter. Lungfish

switch to the torpor state if their pool dries out;

tenrecs switch to the torpor state if food is scarce during

the summer in Madagascar. This prolonged and deep torpor

during summer months is known as

aestivation. Black bears, although often thought of as hibernators,

do not truly enter a state of torpor:

while their body temperatures lower along with

respiration and heartbeat, they do not decrease as

significantly as most animals in a state of torpor,

and bears are still responsive.^[3] Still, there is much

debate about this within the scientific community:

some feel that black bears are true hibernators that

employ a more advanced form of hibernation.^{[citation needed]}

Bats, especially species in temperate regions suffering

harsh winters,

rely upon torpor to survive.

Lowering the body temperature to the ambient temperature

allows them to enter torpor for prolonged

periods at a lower metabolic cost. Oxygen consumption,

heart rate and breathing rates are all lowered

significantly meaning less energy is required to survive.

Torpor is important in daily cycles to conserve

energy as well as prolonged torpor, or hibernation.

Pre-hibernation feeding builds up layers of fat which

are used as the energy source during torpor.

Arousal from torpor in bats is facultative, not obligate,

but comes at a high energy cost, meaning awakening

must be for a good reason.

Dormancy

From Wikipedia, the free encyclopedia

During winter dormancy, plant metabolismvirtually comes to a standstill due, in part,

to low temperatures that slow chemical activity.^[1]

Dormancy is a period in an organism's life cycle when growth, development,

and (in animals) physical activity

are temporarily stopped. This minimizes metabolic activity and therefore

helps an organism to conserve energy.

Dormancy tends to be closely associated withenvironmental conditions.

Organisms can synchronize entry to a

dormant phase with their environment 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 are used by many plants 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 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.

Brumation

From Wikipedia, the free encyclopedia

Dormancy in reptiles is an example of brumation, which is similar to hibernation.^[2]^[3] It differs from hibernation in the metabolic processes involved.^[4]

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.

Diapause

From Wikipedia, the free encyclopedia

Diapause is a predictive strategy that is predetermined by an animal's genotype.

Diapause is common in insects, 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 to the uterine lining ensures that offspring are born in spring,

when conditions are most favorable.

Embryonic diapause is also known as delayed implantation.

Hibernation

From Wikipedia, the free encyclopedia

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 changes, including decreased heart rate (by as much as 95%) and decreased body temperature. Animals that hibernate include bats, ground squirrels and other rodents, mouse lemurs, the European Hedgehog and other insectivores, monotremes and marsupials.

This is a close-up of a Panamint Red Rattlesnake. You can see the loreal pit between and below the eye and the nostril.

Loreal pit

The Loreal pit is the deep depression, or fossa, in the loreal area on either side of the head in crotaline snakes (pitvipers). It is located behind the nostril and in front of the eye, but below the line that runs between the centers of each. It is the external opening to an extremely sensitive infrared detecting organ. The loreal pit is bordered by lacunal scales.^[1]

From Wikipedia, the free encyclopedia

fossa /fos·sa/ (fos´ah) pl. fos´sae [L.] a trench or channel; in anatomy, a hollow or depressed area.

Heat Vision

Rattlesnakes and other pit vipers have remarkable heat-sensing pits. Located behind each nostril, below a straight line that would directly connect the nostril to the eye, is a loreal pit (called this because it is a depression in the loreal scale). These pits are highly effective in detecting differences in temperature even several yards away. At short ranges within a foot or so, minute differences (of perhaps fractions of a degree) may be perceived.

Heat given off by an animal creates a heat image; therefore, rattlesnakes have “heat vision.” The heat images are integrated with visual ones in the brain. This type of vision is helpful for nocturnal predators, for it enables them to hunt effectively even in total darkness. It may also help distinguish predator from prey, allowing rattlesnakes to determine whether they are at risk themselves. Larger, non-prey animals give off larger heat images, signaling the snakes to avoid potential encounters with these animals.

This is from www.desertmuseum.org