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Both snake and weasel hibernate. Which of the following is correct?
A. They will die when temperature decreases below the critical temperature.
B. Weasel will die when temperature decreases below the critical temperature.
C. Snake will die and weasel will wake up when the temperature decreases below the critical temperature.
D. Weasel keeps low body temperature and slow heart rate during the entire period of hibernation.
I don't think any of them should die, they would have some adaptation to prevent that. So,is the answer (D) ?
What is the snake's adaptation in this situation ?
Weasels don't hibernate. See http://icwdm.org/handbook/carnivor/Weasels.asp
Both will die when the temperature falls below a certain level. The difference between snakes (ectotherms) and weasels (endotherms) is that the snake's body temperature will fluctuate more, depending on the surrounding temperature.
An endotherm (from Greek ἔνδον endon "within" and θέρμη thermē "heat") is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine metabolism, but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production. Examples include special-function muscular exertion such as shivering, and uncoupled oxidative metabolism such as within brown adipose tissue. Only birds and mammals are extant universally endothermic groups of animals. Certain lamnid sharks, tuna and billfishes are also endothermic.
In common parlance, endotherms are characterized as "warm-blooded". The opposite of endothermy is ectothermy, although in general, there is no absolute or clear separation between the nature of endotherms and ectotherms.
How do ectothermic organisms regulate their body temperature?
By various behavioral & physiological mechanisms that relies almost completely on the environment.
Ectotherms have no internal heat regulation mechanism like endotherms. Thus, making them heavily reliant on external heat sources to maintain their bodies in a physiologically functioning temperature.
These mechanisms can be classified into two different ways:
1) Behavioral Mechanisms:
Mainly means absorbing heat from the sun during the day or before heat-reducing activities (flying, swimming) and taking shelter from high sources of heat.
This is why you see butterflies, reptiles, frogs, and other ectotherms bask in the sun with their body spread out to increase the surface area for more heat absorption. And when it's too hot, you see them hiding in the shade or near bodies of water.
Some animals exhibit group behavioral mechanisms. A good example is how honey bees cuddle together in large groups to retain & generate heat (it should be noted that this is also an attack mechanism for larger prays attacking the beehive). A similar example is how some gregarious caterpillars bask in the sun in large groups to cluster heat.
B) Physiological Mechanisms:
These act in a similar but not identical to endotherms heat regulation. They vary from molecular level mechanisms, organ level mechanisms, and body level mechanisms.
Molecular level example increase or decrease of cell phospholipid saturation to increase or decrease melting point of call membrane and other cellular organelles.
Organ level examples heat exchange between the cold blood coming from the skin with hot blood coming from the core. Another example is the increased secretions of mucus on some amphibians' skins to cool the body with evaporation.
Body level example torpor of animals for different periods of time to conserve energy and heat. It can occur on daily basis or up to several years (hibernation).
Homeostasis – Ectotherms
Ectotherms make up all the other animals. They have no thermal insulation and so need external sources to warm themselves up. They can’t shiver to warm up either because they’re unable to respire fast enough to make the amount of ATP required for rapid muscle contractions. Instead, ectotherms, like reptiles, rely on thermoregulatory behaviour.
Lizards are a good example. If they want to gain heat they lie on warm ground then get up again when they’re too hot. They change their angle to the sun so that they can control the amount of heat they receive. To prevent themselves from overheating they find shade in vegetation or under rocks. Then, at night, they reduce the amount of heat they lose by insulating themselves in burrows.
The main advantage of being an ectotherm is that they don’t use and therefore don’t need as much energy as endotherms. In fact, it’s possible for ectothermic animals to survive weeks without consuming anything. They have a much slower metabolic rate which drops even further at night when their internal core temperature drops with the colder surrounding temperature. The disadvantage is, however, that they move more slowly at certain times of the day which makes them easy prey and inefficient predators.
Hibernation and gas exchange
Hibernation in endotherms and ectotherms is characterized by an energy-conserving metabolic depression due to low body temperatures and poorly understood temperature-independent mechanisms. Rates of gas exchange are correspondly reduced. In hibernating mammals, ventilation falls even more than metabolic rate leading to a relative respiratory acidosis that may contribute to metabolic depression. Breathing in some mammals becomes episodic and in some small mammals significant apneic gas exchange may occur by passive diffusion via airways or skin. In ectothermic vertebrates, extrapulmonary gas exchange predominates and in reptiles and amphibians hibernating underwater accounts for all gas exchange. In aerated water diffusive exchange permits amphibians and many species of turtles to remain fully aerobic, but hypoxic conditions can challenge many of these animals. Oxygen uptake into blood in both endotherms and ectotherms is enhanced by increased affinity of hemoglobin for O₂ at low temperature. Regulation of gas exchange in hibernating mammals is predominately linked to CO₂/pH, and in episodic breathers, control is principally directed at the duration of the apneic period. Control in submerged hibernating ectotherms is poorly understood, although skin-diffusing capacity may increase under hypoxic conditions. In aerated water blood pH of frogs and turtles either adheres to alphastat regulation (pH ∼8.0) or may even exhibit respiratory alkalosis. Arousal in hibernating mammals leads to restoration of euthermic temperature, metabolic rate, and gas exchange and occurs periodically even as ambient temperatures remain low, whereas body temperature, metabolic rate, and gas exchange of hibernating ectotherms are tightly linked to ambient temperature.
Endotherms vs. Ectotherms!
Have you ever wondered what difference is between endotherms and ectotherms?In general, if an organism uses energy to regulate its body temperature internally, then it is considered endothermic. If an organism instead relies on external environmental factors to regulate its body temperature, then it is considered ectothermic. There are pros and cons to each of these methods of regulating body temperature.
To be endothermic, an organism must produce its own body heat through metabolism. This means that the endothermic organism can maintain internal homeostasis regardless of the external environmental temperature. This ability is commonly referred to as being warm-blooded and probably sounds familiar because of the fact that mammals are warm-blooded, thus making us endotherms. An example is seen in the image below, the young kitten. This is why during winter or summer temperatures, humans will maintain an internal body temperature of around 98.6 degrees Fahrenheit.
Once we understand that we are endotherms, we can then understand better why we sweat or shiver when we are hot or cold. These actions are regulatory reactions from our body trying to maintain internal homeostasis while being exposed to differing external temperatures. The sweat we produce during hot days is actually helping to cool our bodies down and we shiver during cold days to keep our bodies warm. Being an endotherm allows an organism to survive in many diverse environments, but can be extremely energy demanding.
On the other hand, an organism that relies on the temperature of the environment around them to regulate their internal body temperature requires much less energy. This type of organism is called an ectotherm and commonly referred to as being cold-blooded. Great examples of ectothermic organisms are reptiles and fish. In the image below an example reptile is shown. Since these organisms rely on the environment for body temperature regulations, they exhibit different behaviors in reaction to changing external temperatures. In order for an ectotherm to warm up it would bask in the sun, or if it needed to cool down it could burrow or seek shade. These are physical interactions with the environment since the ectothermic organism can not rely on physiological processes like the endotherm (such as sweating and shivering).
So depending on if an organism is and endotherm or ectotherm, it will exhibit varying behaviors in order to survive and function at optimal level in their environment. Some examples are:
-Fish migrating to warmer/colder water as needed during season changes.
-Lizards coming out of burrows to bask in the sun in order to warm their bodies.
-Humans shivering during a cold night hike.
-Sea lions holding their flipper out of the cold ocean water to warm up.
Hopefully this has helped to clarify the main difference between endotherms and ectotherms. There is much more to be learned about these organisms and I hope this information helps encourage you to learn more about them.
4 INTERGENERATIONAL EFFECTS OF CLIMATE CHANGE ON AGEING RATES IN ECTOTHERMS
Stress experienced by parents can influence the physiology of their offspring. To establish whether the environmental conditions experienced by parents can influence the rates of ageing of their offspring, we need to understand the mechanisms whereby rates of ageing could be transmitted between generations. In the absence of detailed information on life expectancy (not normally available over multiple generations), the usual approach is to use a biomarker of the rate of ageing, such as telomere length. Telomere length at a given developmental stage is a function of their initial length (i.e. at zygote), minus the accumulated shortening, plus the amount of restoration experienced until that point (Dugdale & Richardson, 2018 ).
Heritability estimates for telomere length in animals range from 0.18 to >1 (reviewed in Dugdale & Richardson, 2018 Haussmann & Heidinger, 2015 Reichert et al., 2015 ), tending to be higher when measured earlier in life (Dugdale & Richardson, 2018 ). However, in ectotherms (in contrast to most endotherms), telomeres show signs of elongation after birth in several species (reptiles: Ujvari et al., 2017 fish: McLennan et al., 2018 amphibians: Burraco et al., 2020 ). This makes it far from straightforward to decide the point in ontogeny at which telomere length should be compared between parents and offspring.
If climate warming causes a reduction in the physiological condition of ectotherms at the time of breeding, this could lead to shorter telomeres in their offspring through two different routes. First, stressors could affect germline telomere lengths, causing offspring to inherit shorter telomeres from parents that were exposed to more stressful environments. Second, indirect parental effects can cause faster ageing in offspring, either during the embryonic stages (e.g. through maternally derived stress hormones or suboptimal temperatures during development), or in the early post-natal stages (e.g. through changes in parental behaviour or care Haussmann & Heidinger, 2015 ). Both routes may be particularly important for ectotherms in a warming world because higher temperatures can induce maturation earlier in life and at a smaller size (Angilletta, Steury, & Sears, 2004 ). Smaller size at breeding is often associated with the production of lower-quality offspring and poor parental care, which can negatively affect offspring performance at embryonic and post-birth stages (Angilletta et al., 2004 ), and cause accelerated ageing (Haussmann & Heidinger, 2015 Figure 1c). Detrimental thermal conditions experienced by parents can lead to poor offspring condition as a consequence of a reduction in the energy invested by the parents in each offspring. However, although rare, compensatory responses by parents or changes in breeding strategies could mitigate this effect, for example by reducing clutch size to allocate a larger amount of energy to each offspring (Charnov & Ernest, 2006 ).
There are several other factors that ideally should be considered when studying the intergenerational effects of warming on ageing dynamics in ectotherms. Many ectotherms show sexual dimorphism, with females typically larger than males, and temperature-dependent sex determination during embryogenesis can also occur. The negative consequences on ageing caused by warming may be exacerbated in species producing females at higher incubation temperatures. Embryos developing as females, and hatching at smaller sizes due to warming, could then show compensatory growth responses, which may result in a lifespan penalty (Metcalfe and Monaghan, 2003 ). Sex differences in lifespan and ageing can also be driven by the reproductive strategy of species. For example, in polygynous species, survival declines with age faster in males than in females (Clutton-Brock & Isvaran, 2007 ) warming could exacerbate such sex differences in lifespan by uncoupling the time at which each sex reaches sexual maturation, a process that may be particularly important in semelparous species.
Ectotherms’ cardiovascular upgrade for endothermic lifestyle
Keeping warm has its advantages. Endotherms, which maintain a constant raised body temperature, keep going no matter how chilly their surroundings. Meanwhile, ectotherms are at the behest of the environment: many have to sit tight until they have absorbed enough warmth to function. But which physiological systems did our ectothermic ancestors have to upgrade for us to benefit from internal central heating? Stanley Hillman from Portland State University, USA, and Michael Hedrick from California State University East Bay, USA, explain that there are two competing theories: that ectotherms increased the number of mitochondria in muscle and modified the energy-producing organelles to upgrade to an endothermic lifestyle or, our ancestors expanded the cardiovascular system to supply the additional oxygen required to fuel our costly, high-temperature way of life. With evidence stacking up on both sides, Hillman and Hedrick decided to review the differences between the cardiovascular systems of ectotherms and endotherms to find out whether expanding the cardiovascular system allowed endotherms to turn up the thermostat.
First, the duo scoured the literature for cardiovascular measurements from a wide range of exercising animals – from ectothermic fish and amphibians to endothermic birds and mammals – to put their theory to the test. But there was one glaring omission: ‘a gap existed in the data for reptiles for [cardiac] flow and pressure during exercise’, they say, before accepting – after contacting many colleagues – that the measurements have yet to be made. However, despite the setback, they interrogated the data to identify differences between the cardiovascular systems of exercising ectotherms and endotherms to find out just how hard the animals’ hearts can work.
Calculating the vascular conductance, cardiac power and work done per heart beat (stroke work), Hillman and Hedrick found that endotherms’ hearts pumped blood at a higher pressure (17.1 kPa vs 3.3 kPa for the ectotherms) and at a higher heart rate (∼5 beats s –1 compared with the ectotherms’ ∼1 beat s –1 ), allowing the exercising endotherms to produce higher exercise cardiac power. And when they compared the relative size of the endotherms’ and ectotherms’ hearts, they found that the endotherms’ larger hearts enabled them to increase their blood pressure. They say, ‘A major difference between ectotherms and endotherms is the large increase in blood flow rates’, which is largely due to their higher heart rates and allows endotherms to increase the oxygen supply to the power-hungry muscles that keep them warm. However, the duo also found every mW of cardiac power supports a remarkable 158 mW of aerobic power output (which is only 0.6% of the exercise aerobic energy expense) regardless of the animal's lifestyle, showing that the cost of circulation is low for endo- and ectotherms alike.
Focusing on the cardiac changes that were essential for ectotherms to warm up, Hillman and Hedrick explain that our ancestors had to remove the cardiac shunts – which allow amphibians and reptiles to mix oxygenated and deoxygenated blood – to increase oxygen transport. They also had to increase their heart rates by developing the sarcoplasmic reticulum – which controls the calcium levels in muscle that regulate muscle contraction – to increase the heart rate. And finally, endotherms had to increase their cardiac muscle mass relative to the body mass of similarly sized ectotherms to produce the higher blood flow rates that are essential for a metabolically demanding endothermic lifestyle.
The duo says, ‘These results suggest that a key step in the support of endothermy was the greatly enhanced ability of the cardiovascular system to deliver oxygen which accounted for the approximately ten-fold increase in aerobic scope between endotherms and ectotherms’.
Ectotherms vs. endotherms
Do you know the difference between an ectotherm and an endotherm—or even what these terms mean? They both refer to the ways that animals stay warm. When the weather outside is frightful, a blog post about thermoregulation is so delightful! Keep reading to find out which animals need help from the environment to stay warm (ectotherms), and which animals produce their own heat (endotherms).
For these animals, heat comes from outside (ecto-) their bodies—their environment provides their warmth. That means they require less food, and are consequently able to inhabit places that would be off-limits to endotherms. However, their activity level is limited by the surrounding conditions. If it gets too cold, they simply can’t move.
Banggai cardinalfish (Pterapogon kauderni)
Like most fish, Banggai cardinalfish are ectotherms. Because of this, these fish appear less hungry during winter months.
Widehand hermit crabs (Elassochirus tenuimanus)
Hermit crabs, along with all invertebrates, are ectotherms. Since invertebrates account for more than 95 percent of animal species, that means that most animals are ectotherms
Tripod fish (Family Ipnopidae)
These fish live in the abyssal zone, where conditions are so stable that their body temperatures don’t change.
These animals produce their own heat inside (endo-) their bodies. Creating that warmth speeds up their body processes: muscles, neurons and all of their processes work faster. That also means they require a lot of food—between five and 20 times more food than an ectotherm of the same size!
Sea otters (Enhydra lutris)
These marine mammals have to eat roughly 25 percent of their body weight per day to keep their bodies warm.
Anna’s hummingbirds (Calypte anna)
These high-energy birds have needs that can’t be met at night when they’re at rest. The solution? Torpor, a state of deep sleep and lowered metabolism. Some animals extend torpor over the whole winter this is called hibernation.
Opahs (Lampris guttatus)
These fish generate heat mainly by constantly flapping their pectoral fins, which helps their bodies stay warmer than the water even when they dive over 1,500 feet below the surface. Opahs have been sighted in Washington waters twice since 1935.
Endotherm vs. Ectotherm
The hypothalamus, which provides the highest level of endocrine control, integrates the activities of the nervous and endocrine systems.
The hypothalamus plays an important role in regulating the body temperature. This function is carried out by the anterior hypothalamus and the posterior hypothalamus. They have directly opposite effects.
Stimulation of the anterior hypothalamus begins a thermolytic response thereby resulting in decrease in the body temperature. While stimulation of the posterior hypothalamus begins a thermogenic response that leads to elevation in body heat and its conservation.
Thermolytic responses are characterized by cutaneous vasodilation which is illustrated by body reactions like elevation in heat loss by radiation, perspiration that facilitates heat loss by evaporation, and the typical feature of panting in animals particularly in dogs.
Thermogenic responses incorporate cutaneous vasoconstriction that results in minimizing loss of heat via radiation, the mechanism of shivering that increases heat level owing to vigorous muscular activity.
The hypothalamus is also well equipped to gauge the fluctuations in the temperature of the blood circulating within the body and so will respond.
An ectotherm is an organism in which internal physiological sources of heat play a minimal or insignificant role in regulating body temperature. Such species (for example, frogs) rely on external heat sources, allowing them to function at very low metabolic rates.
Some of these animals live in habitats with nearly constant temperatures, such as those found in the abyssal ocean, and can thus be classified as homeothermic ectotherms. In comparison, many species habitually seek out external sources of heat or shelter from heat in areas where temperature varies so widely as to restrict the physiological behaviours of other types of ectotherms for example, many reptiles control their body temperature by basking in the sun or finding shade when required, in addition to plenty of other behavioural thermoregulation mechanisms. Owners of pet reptiles in home captivity can use a UVB/UVA light device to aid the animals' basking behaviour. Endotherms, unlike ectotherms, largely depend, if not entirely, on heat produced by internal metabolic processes, while mesotherms adopt an intermediate strategy.
Fluctuating ambient temperatures may have an effect on body temperature in ectotherms. The word for such variations in body temperature is poikilothermy, though the definition is not generally accepted and its usage is diminishing. Poikilothermy is practically absolute in small aquatic creatures like Rotifera, but other creatures (like crabs) have more physiological choices, and they can switch to desired temperatures, prevent ambient temperature changes, or moderate their effects. Ectotherms, especially aquatic species, may exhibit homeothermic characteristics. Normally, their ambient environmental temperature range is relatively constant, and few seek to sustain a higher internal temperature due to the high associated costs.
Ectotherm, any cold-blooded animal—that is, any animal whose body temperature control is dependent on external sources such as sunlight or a heated rock surface. Fishes, amphibians, reptiles, and invertebrates are all ectotherms.
Ectotherms' body temperature is primarily determined by external heat sources. That is, the temperature of an ectotherm's body rises and falls in tandem with the temperature of the ambient world. Although ectotherms, like all living things, produce metabolic heat, ectotherms cannot increase this heat output to maintain a particular internal temperature. However, most ectotherms do control their body temperature to some extent. They simply do not do so by generating heat. Instead, they employ other techniques, such as actions (seeking light, shade, and so on) to identify conditions that fulfil their temperature requirements.
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Why Regulate Temperature?
Most animals have certain basic body temperature limits that they must adhere to in order to survive. Water freezes at 0 degrees Celsius, end text to form ice, at the other end of the spectrum. As ice crystals grow within a cell, the membranes are usually ruptured. At temperatures above 40 degrees Celsius, enzymes and other proteins in cells often lose shape and function, a process known as denature.
Why do many organisms, like you and me, keep our body temperatures within such a small range? Temperature affects the rate of chemical reactions, both because it affects the rate of collisions between molecules and because the enzymes that regulate the reactions can be temperature sensitive. Reactions tend to be quicker at higher temperatures, up to a point where their rate dramatically decreases as their enzymes denature.
Each species has its own metabolic network and collection of enzymes that are adapted for a specific temperature range. Organisms ensure the proper activity of their metabolic reactions by maintaining their body temperature within the target range.
Ectothermic Heating and Cooling
Many ectotherms exist in environments with little control, such as the ocean, where the ambient temperature is relatively constant. Crabs and other ocean-dwelling ectotherms can move to desired temperatures when required. Ectotherms who live mostly on land can control their temperature by basking in the sun or cooling off in the shade. Some insects warm themselves by vibrating the muscles that power their wings rather than flapping their wings. Ectotherms are slow at night and early in the morning due to their reliance on environmental factors. Many ectotherms must warm up before becoming involved.
Ectotherms in the Winter
Many ectotherms undergo torpor, a condition in which their metabolism slows or stops, during the winter months or when food is scarce. Torpor is essentially a short-term hibernation that can last anywhere from a few hours to an entire night. Torpid animals' metabolic rates will drop by up to 95% of their resting rate.
Ectotherms can also hibernate, which can last a season or, in the case of certain species like the burrowing frog, years. Hibernating ectotherms have a metabolic rate that is one to two percent of the animal's resting rate. Tropical lizards do not hibernate because they have not adapted to cold weather.
Certain ectotherms can control their body temperature to a useful degree thanks to a variety of behavioural patterns. Reptiles and many insects seek out sunny areas and locations that maximise their exposure to warm up at dangerously high temperatures, they seek shade or cooler water. Honey bees huddle together to keep warm in cold weather. Butterflies and moths can orient their wings to maximise exposure to solar radiation before taking flight in order to build up heat. For thermoregulation, gregarious caterpillars such as the forest tent caterpillar and fall webworm benefit from basking in large groups. Many flying insects, including honey bees and bumblebees, increase their internal temperatures endothermically before flight by vibrating their flight muscles without violently moving their wings. This form of endothermal operation exemplifies the difficulty in applying words like poikilothermy and homeothermy consistently.
Physiological adaptations, in addition to behavioural adaptations, aid ectotherms in temperature regulation. Diving reptiles retain heat by heat exchange processes, in which cold blood from the skin takes up heat from blood flowing away from the body heart, reusing and thereby conserving some of the heat that would otherwise be lost. When it is humid, the skin of bullfrogs secretes more mucus, allowing for more evaporation cooling.
During cold periods, some ectotherms reach a state of torpor, in which their metabolism slows or, in some cases, stops completely, as in the case of the wood frog. Torpor can last for an hour, a season, or even years, depending on the species and circumstances.
Some species may alter their body chemistry in colder environments, where ectotherms may be exposed to freezing temperatures, to limit the growth of ice crystals in their cells and tissues or to prevent ice crystal formation entirely. Many ectotherms can produce and flood their bloodstream and tissues with cryoprotectants, which are ice-inhibiting compounds such as proteins, sugars, and sugar alcohols (e.g., sorbitol and glycerol), or they can use dissolved substances already present in the bloodstream, such as salts. These adaptations keep the cells of the animals from freezing by lowering the freezing point of water. The wood frog (Lithobates sylvatica), for example, survives the winter by producing excess sugars (specifically, by converting glycogen into glucose) that protect the animal's cells and tissues, despite the fact that much of the water in the frog's body may freeze. Similarly, ray-finned fishes that live in polar marine environments have high internal salt concentrations that prevent freezing, as well as glycoproteins that function as cryoprotectants.
Pros and Cons
Ectotherms depend heavily on external heat sources, such as sunlight, to maintain their optimum body temperature for a variety of bodily activities. As a result, they depend on ambient conditions to achieve operational body temperatures. Endothermic animals, on the other hand, sustain nearly constant high operating body temperatures primarily through the use of internal heat provided by metabolically active organs (liver, kidney, heart, brain, muscle) or even specialized heat generating organs such as brown adipose tissue (BAT). For the same body mass, ectotherms usually have lower metabolic rates than endotherms. As a result, endotherms typically consume more food, and typically food with a higher energy content. Such specifications can restrict a given environment's carrying capacity for endotherms in comparison to its carrying capacity for ectotherms.
Ectotherms are more sluggish at night and in the early mornings because they depend on environmental factors to regulate their body temperature. Many diurnal ectotherms need to warm up in the early sunlight after emerging from their shelter before they can begin their daily activities. Most vertebrate ectotherms' foraging behaviour is therefore limited to the daytime in cool weather, and in cold climates, most cannot live at all. Most nocturnal lizard species, for example, are geckos that specialise in "sit and wait" foraging strategies (see ambush predator). Such techniques do not necessitate as much energy as active foraging and do not necessitate as much hunting activity. From another perspective, sit-and-wait predation can necessitate extremely long periods of ineffective waiting. Endotherms, in general, cannot tolerate such long periods without food, however appropriately adapted ectotherms can. Endothermic vertebrate organisms are therefore less dependent on environmental factors and have evolved greater variability (both within and between species) in their daily activity patterns.
Ectotherm, any cold-blooded animal, that is, any animal whose body temperature control is dependent on external sources, such as sunlight or a heated rock surface. Fishes, amphibians, reptiles, and invertebrates are all ectotherms. An aquatic ectotherm's body temperature is normally very similar to the temperature of the surrounding water. Ectotherms do not consume as much food as warm-blooded animals (endotherms) of the same age, but they are more sensitive to temperature changes. Ectotherms that live in areas where temperatures fluctuate seasonally escape extremes by seeking refuge in burrows or similar locations, or by going dormant to some extent. Furthermore, ectotherms use biochemical techniques to counteract the effects of high temperatures. Ectotherms release heat-shock proteins during times of heat stress, which help stabilise other proteins and thus avoid their denaturation, since excessive heat can kill proteins in an animal's body.