How Is Hibernation Different from Aestivation?
There are different ways of adapting to the drastic changes in the weather conditions that animals perform to escape the lack of food and activities. One of the best methods is hibernation. It is a process where the metabolic conditions suspend to a minimum level resulting in an escape from the extreme winters for months. Here, we will study how these animals hibernate and what is its difference from aestivation.
The special process of suspending the metabolic activities by staying inside a nest or den and going to deep sleep to avoid the extreme weather conditions in winter is called hibernation. It is a technique where the insects and animals learned how to survive the chilliest days and nights without foraging or predating outside and stay inside their nests. They don’t need to migrate to someplace warmer to stay, rather trim down the basic metabolic activities to the lowest and conserve energy to survive for months.
In this aspect, animals often do the same thing to overcome the harsh climates of summer in arid regions. They also suspend their metabolic activities and conserve water to survive harsh summers. This process of survival is called aestivation. With this unique physiological phenomenon, animals and insects escape the lack of food, drought, and extreme heat. We will discuss the difference between hibernation and aestivation later.
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What is the Process of Hibernation?
As mentioned earlier, the process of hibernation is a physiological state where an animal’s body becomes inactive by suspending various internal involuntary actions such as heart rate, breathing rate, and metabolism. Most of the organs and tissues remain inactive and the requirement of energy reduces to a minimum. The oxygen intake reduces to almost 10% and the body temperature reduces considerably. This is the reason why animals start accumulating energy deposits and trim down their metabolic and physiological activities to trim down energy requirements. This process is what you will find common among all hibernating animals in nature.
Which Animals Undergo Hibernation?
Only those animals that live in a harsh climate undergo hibernation or aestivation. The animals that hibernate are listed below.
Bumblebees
There is a single queen in the entire hive and she needs to be protected from any threat. Now that we know what is hibernation, we can easily state that the queen does the same during the winter months whereas the worker bees die outside.
Squirrel
Squirrels also do the same and escape the harsh winters by sleeping off these months entirely. Almost all species living in harshly cold climates perform winter hibernation.
Bats
This is something out of the box. Bats can resume their hibernation after a small stint of searching or hunting for food. After the winter is over, they regain their normal physiological activities.
Turtles
Some types of hibernating turtles live in colder places where winter is harsh. Those who are living in a hot climate don’t hibernate but might aestivate. In fact, turtles living in hotter climates aestivate to get rid of the extreme heat and regain their physiological activities when rainfall or winter arrives.
Snakes
Snakes escape winters by hibernating. This activity has a specific term called brumation. This term is used to classify hibernation in reptiles.
These are a few examples of animals that hibernate. Let us proceed to the process of aestivation.
Which Animals Perform Aestivation?
As described earlier, it is a stage of dormancy where animals suspend their metabolic activities and go to a hibernating stage to avoid extreme heat and droughts is called aestivation. The best examples of the aestivation are listed below.
Mollusca
Snails often aestivate to avoid extreme heat and drought during the summer season. Some move to the shaded regions to preserve water.
Arthropods
Lady beetles and mosquitoes aestivate during the summer season and survive the extremely dry conditions. They regain their physiological activities once the rainy season appears. Australian crabs aestivate due to lack of food during the summer season.
Reptiles
Desert tortoises and crocodiles aestivate in the North American deserts.
Amphibians
Greater siren and cane toads aestivate to avoid hot climates. They move underground into someplace cooler and preserve their body energy.
Difference between Hibernation and Aestivation
Hibernation is commonly called winter sleep whereas aestivation is summer sleep. The former takes place longer than the latter. In fact, a winter sleep is conducted in a warmer place than the freezing external environments. The aestivation, summer sleep, on the other hand, takes place under the shade of trees or underground where the temperature drops significantly.
Hibernation protects an animal from internal organ damage due to plummeting temperatures. On the contrary, aestivation protects an animal from loss of water and organ damage at the same time.
A hibernation period is witnessed in warm and cold-blooded animals. Aestivation is witnessed in only cold-blooded animals.
This is all you need to know about hibernation and aestivation. The differences between these two exceptional physiological activities performed by hybernating and aestivating animals are important to note as these two processes are not the same. More examples of hibernating animals will help you in understanding the concept and learning how this process can save an animal’s life from harsh climatic conditions.
FAQs on Hibernation in Biology: Meaning, Process & Examples
1. What is hibernation in Biology?
Hibernation is a state of prolonged dormancy or inactivity that certain animals undergo to survive harsh winter conditions. It is an evolutionary adaptation characterised by a significant drop in metabolic rate, heart rate, breathing, and body temperature. This process allows animals to conserve energy when food sources are scarce and temperatures are extremely low.
2. What are some examples of animals that hibernate?
Many animals across different classes exhibit hibernation to survive cold seasons. Common examples include:
Mammals: Bears, bats, groundhogs, hedgehogs, and squirrels.
Reptiles: Many species of snakes, turtles, and lizards.
Amphibians: Frogs and salamanders, which often burrow in mud.
Insects: Certain species of bees and butterflies.
3. What is the difference between hibernation and aestivation?
Hibernation and aestivation are both forms of dormancy, but they are triggered by different environmental conditions. Hibernation is a state of inactivity during the winter to escape cold and food scarcity. In contrast, aestivation (or estivation) is a state of dormancy during the summer to survive extreme heat, drought, and lack of water.
4. Is hibernation the same as sleeping?
No, hibernation is physiologically very different from sleeping. While sleep is a light state of rest from which an animal can be easily woken, hibernation is a much deeper state of metabolic depression. During hibernation, an animal's body temperature can drop to near freezing, and its heart rate can slow to just a few beats per minute. Waking from hibernation is a slow and energy-intensive process, unlike waking from sleep.
5. What physiological changes occur in an animal's body during hibernation?
During hibernation, an animal's body undergoes several profound physiological changes to conserve energy. These include:
A drastic reduction in metabolic rate, sometimes to as low as 1% of the normal rate.
A significant drop in body temperature, often aligning closely with the ambient temperature of their den.
A severe slowing of the heart rate and breathing.
Suspension of non-essential activities like digestion and growth, with the animal surviving solely on its stored fat reserves.
6. Why do animals need to hibernate?
The primary purpose of hibernation is survival. It is a critical strategy to overcome periods when the energy cost of staying active is higher than the energy that can be gained from available food. By entering a state of dormancy, animals avoid the challenges of extreme cold, lack of food, and the high metabolic cost of maintaining a constant body temperature, thereby increasing their chances of surviving until favourable conditions return.
7. What is the difference between hibernation and torpor?
Torpor is a general term for a state of decreased physiological activity in an animal, usually characterised by a reduced body temperature and metabolic rate. Hibernation can be considered a prolonged, seasonal form of torpor that lasts for weeks or months. In contrast, some animals, like hummingbirds and bats, enter a state of daily torpor that lasts for shorter periods, often less than 24 hours, to conserve energy overnight or during inactive parts of the day.
8. What are the main dangers an animal faces during hibernation?
While hibernation is a survival mechanism, it comes with significant risks. The primary danger is predation, as the hibernating animal is helpless and cannot flee or defend itself. Other dangers include depleting fat reserves before the end of winter, freezing to death if the den is not sufficiently insulated, or waking up too early due to unseasonal weather, which can lead to starvation.
9. Can humans hibernate?
No, humans cannot naturally hibernate. Our physiology is not adapted to withstand the extreme drops in body temperature and metabolic rate required for true hibernation. However, the medical field uses a similar concept called therapeutic hypothermia, where a patient's body temperature is intentionally lowered to reduce metabolic demand and protect the brain and other organs during major surgery or after events like cardiac arrest.
