You might have heard about bears going into a deep sleep, but have you ever wondered why they do so? If you want to know the answer to this question, this article is going to help you with that. In this article, you will read about Hibernation and Diapause and what are the major differences between them.
Many species, such as butterflies and bats, hibernate to avoid having to hunt for food or transfer to a warmer region during the cold, dark winters. They slow down their metabolisms to conserve energy. Animals in hot climates go through aestivation, which is a sort of Hibernation. This functions similarly, allowing them to withstand extreme heat, drought, and food scarcity. But Hibernation can't be described just as sleeping. It can range from protracted, deep unconsciousness to brief periods of inactivity, depending on the species.
Hibernation, however, has its drawbacks, as the hibernating animal is vulnerable to predators and unpredictable weather.
Certain organisms survive the periodic harsh conditions like environmental changes, scarcity of food, temperature changes, etc. by going into a dormant state. It is the state characterized by minimum or no metabolic activity in the body of the organism. Dormancy is a temporary phase in which an animal’s physical activity, growth and development are paused. This helps the organisms to conserve energy by practically being inactive or sleeping through the harsh phase. The kind of dormancy varies from organism to organism. Some go into a Hibernation state in which animals remain in a dormant state with the fall in temperature. On the other hand, Diapause is a state of dormancy mostly seen in insects in which the growth of the insect is suspended for a while.
Let’s learn more about Hibernation and Diapause and the major difference between them in this section.
What is Hibernation?
Hibernation can simply be defined as the state in which organisms reduce the metabolic rate of their body when food is scarce, usually in winters. The animals that undergo Hibernation are hamsters, chipmunks, dormice, bats, hedgehogs, etc. Some other insects, amphibians, and reptiles also go into Hibernation. In terms of birds, only the North American common poorwill goes into Hibernation completely. This wonderfully disguised nocturnal bird is a cousin of the British nightjar and spends the winter hibernating among rocks. It can reduce its oxygen consumption by 90% while its body temperature dips to 5°C, indicating that it is barely alive.
It is a state of minimum metabolic activity in the body of the organism. Hibernation is seasonal and is characterized by low body temperature, lower heart activity, low metabolic rate and so on. It is seen in some endotherms during the wintertime. In this time, the organisms that hibernate go into a state that resembles deep sleep so that their metabolism comes down and they burn less energy.
In the state of Hibernation, the organism slows its breathing, temperature and other vital functions that burn energy. It is mostly a response by the body of organisms to the non-availability of food and low temperature. It may last from a few weeks to months. Rodents like groundhogs mostly go into Hibernation. Other examples are bears, bats, ground squirrels, etc. To hibernate, animals have to eat as much as possible. They eat more and build extra fat layers so that these fat layers are broken down in the Hibernation state to survive.
What is the Mechanism behind Hibernation?
The metabolism of a hibernating animal slows down, and body temperature drops to -2°C in ground squirrels. Bats' heart rates can drop from 400 to 11 beats per minute as their breathing slows. To withstand being frozen solid, some cold-blooded creatures, such as wood frogs, manufacture natural antifreeze.
To get ready for Hibernation, summer and autumn are the seasons when mammals eat the most, building fat to get them through the winter. There are some risks involved in Hibernation as well like lack of fat, harsh weather, or an early waking can all cause animals to perish during Hibernation.
What is Diapause?
Diapause is a natural halt in the development of some animals, characterized by a decrease in metabolic activity. It's found in a variety of insects and mites, as well as a few crabs and snails, and maybe additional animal species. This pause in development appears to be a reaction to the impending arrival of severe environmental conditions. It can happen at any stage of life, but it's most prevalent in pupae (e.g., the cocoons of moths).
Diapause usually occurs when the body's levels of growth and molting hormones fall, which is frequently accompanied by variations in day length, temperature, or food supply. Diapause is caused by genetics, however, it may be prevented in the lab if the animals are given a constant and favorable environment.
Diapause is often seen in insects during their developmental stages. It is a state in which the development of the organisms stops spontaneously by reduction of metabolic activity. It is a period of suspended development in the growing organisms. It may occur at any stage of development of the insect but it is mostly seen in the pupa stage. Diapause occurs when the level of growth hormones decreases in the body of the organism. Thus, it is similar to Hibernation but is marked by a pause in the developmental stages of the organism.
Major Differences between Hibernation and Diapause
Hibernation and Diapause are two examples of animal adaptations to a severe habitat or climate. However, Diapause is most commonly seen in insects and the early stages of an organism's growth (such as an embryo). Hibernation is comparable to Diapause, however, Hibernation is characterized solely by low body temperatures, whereas Diapause lacks this property.
Insects go through Diapause, while higher animals, as well as invertebrates like arthropods, go through Hibernation.