Hibernation and aestivation are two types of sleeping states that occur in two different climates. Both are prolonged forms of torpor.
To survive in harsh and extreme environments, animals will sometimes fall asleep. This sleeping pattern may change depending on the climate and the organism’s growth stage.
The primary distinction between hibernation and aestivation is that the former is for winter sleep and the latter is for summer sleep.
Animals such as bears and crocodiles sleep for extended periods in extremely cold temperatures. To stay alive and conserve energy, they deliberately slow down their metabolic rate, heart rate, and breathing.
Aestivation, which occurs during the summer, is the opposite of hibernation. Animals to protect themselves from hot, dry conditions, which are common in desert areas, use aestivation. Dormancy occurs here as well, with organisms hiding in moist and marshy areas to keep their bodies cool and wet.
The animals can survive in harsh environments thanks to these two sleeping mechanisms. This reduces energy consumption by 70-100 per cent, which is less than the usual time, i.e., in the active state.
What exactly is Hibernation?
During the winter season, certain parts of the world experience freezing temperatures. This could include places like the northern and southern poles, the Arctic and Antarctic regions, and so on.
During this period of extreme cold, the flora and fauna of that particular region suffer the most. To survive in such harsh conditions, they enter a state of dormancy or inactivity, known as hibernation.
In non-technical language, you can think of it as your laptop’s power-saving mode. Assume your laptop is neither on nor off; it is simply resting. It saves whatever work you were doing and switches to power-saving mode. When you turn it back on, it resumes with your data.
Hibernation, on the other hand, is a power-saving mode that conserves energy while protecting the organism from a harsh environment.
What causes Hibernation?
After learning what hibernation is, you may be wondering what it does to protect the organism from extreme cold. So tell us more about it!
The reason for hibernation is obvious. Let us go over some of them.
- Food Availability
Animals rely on plants or other fauna to meet their nutritional needs. Snow and moisture destroy natural vegetation during extreme colds.
Only a few exceptional plants with adapted survival mechanisms can tolerate and grow there.
This is detrimental to the animals that rely on plants for food. Smaller prey, on the other hand, hide or perish in the cold climate. As a result, the number of prey for predating animals decreases.
To reduce their food requirements, hibernators enter a hyperphagic state. They multiply their appetite by consuming as much food as possible to store energy for the entire season.
- To keep the internal temperature stable
The ectothermic organism’s internal body temperature is determined by external climatic conditions. As a result, their internal temperature varies dramatically with changes in the climate.
Thus, some ectothermic organisms hibernate to maintain their body temperature within a specific range. As a result, they are unaffected by the environmental changes occurring around them.
- Energy conservation
Organisms that live in cold climates are acutely aware of the scarcity of food during the winter. Even if they are in a hyperphagic state and want to eat more and more, the food will be depleted if the body consumes energy quickly.
During hibernation, the hibernator attempts to reduce body activity to reduce energy consumption. The metabolic process is nearly halted. Some of the activities that occur during hibernation include decreased breathing and heart rate, no physical movement, and so on. They tend to conserve excess energy use.
Hibernation is divided into three stages: preparation, actual hibernation, and arousal from hibernation.
Beginning of Hibernation
Hibernation is a gradual process that reduces all physical and mental activities within the body. The heartbeat and respiration rate slow to a few times per minute. In addition, the body temperature drops from 37 2°C (101.5 to 103.5°F) to 10-20°C (50 to 68°F). This lower body temperature favours only a few demands and metabolic actions, assisting in energy conservation.
As the electrical impulses are turned off, the brain’s activity stops completely. Only a few of the areas related to the response to external stimuli, such as light, temperature, noise, and so on.
Period of Arousal
Hibernation can be either continuous or intermittent. Large organisms can store a lot of nutrients and remain dormant for the entire season. Smaller animals, such as rodents, cannot store much food while in torpor.
As a result, they emerge at regular intervals to eat, urinate, and defecate. These are shallow hibernators. Shallow hibernators include chipmunks, skunks, squirrels, and raccoons.
The arousal process begins by gradually increasing heart rate and blood flow, as well as dilation of contracted vesicles. In addition, the rate of breathing quickens. Blood begins to circulate throughout the body, particularly around the heart, lungs, and brain. All of these metabolic processes stimulate the organs. It may take several hours for the entire body to be activated.
What exactly is Aestivation?
Aestivation, also known as estivation, is similar to hibernation but occurs during the summer. Hibernation is known as winter sleep, just as aestivation is known as summer sleep. It is a very clever trick used by animals in hot and dry climates to deal with extreme heat.
Aestivation is derived from the Latin word aestvre, which means, “to spend summers.” As a result, we can define aestivation as a specialised method of evacuating heat and surviving easily during the summer.
Aestivation is a long and deep torpor period in zoology that maintains the internal body temperature of ectotherms during the summer. As a result, summer dormancy is commonly used.
Aestivation, like hibernation, is characterised by slow metabolic functioning of the body. This can include a low heart rate, a decrease in respiratory rate, a cessation of brain impulses (except for some required ones), and so on.
What causes the animals to sleep?
Ectothermic organisms face a slew of issues related to body temperature regulation during the summer. They are cold-blooded and thus incapable of maintaining their body’s constant temperature. Instead, their internal temperature fluctuates in response to environmental temperature changes.
When the outside temperature rises above 40-45°C in the summer, their body temperature will eventually reach the same limit. As a result, they undergo aestivation to keep from becoming overheated. It not only protects their bodies from extreme heat, but also from other environmental stresses that occur during the summer. Drought, famine, and water scarcity are just a few examples.
The primary goal of aestivation is the same as that of hibernation: survival in harsh environmental conditions.
Few floras and faunas can thrive in hot and dry climates.
This causes a food shortage during the summer.
During the rainy and winter seasons, the animals try to get the most nutrition possible and then use this stored energy while aestivating.
Furthermore, the dry regions lack an adequate water supply. Aestivation also assists animals in dealing with water scarcity because they do not require water during their summer sleep.
Aside from the foregoing, aestivation aids in the stabilisation of internal organs by keeping them from becoming overheated and desiccated.
What causes Aestivation?
Summer dormancy is caused by hot, dry, and arid climatic conditions. Aestivation can occur in both terrestrial and aquatic ectothermic organisms because of temperature fluctuations.
According to the researchers, this mechanism has evolved over several million years to successfully record and react to extreme temperature conditions. As the summer season approaches, the dryness and heat automatically initiate the aestivation process.
In this blog, we looked at conditions and differences due to which animals hibernate as well as those that aestivate. We discovered the significance of these activities. We also learned why such periods of sleep are necessary for animals living in such areas.
Also published on Medium.