What is the Difference Between Torpor and Hibernation

Mammals, with their high metabolic rates and warm-blooded nature, face challenges in maintaining body temperature, particularly smaller species vulnerable to rapid heat loss. To address this challenge, some animals use specific tactics to conserve energy and regulate body heat. Torpor and hibernation are two such strategies for reducing activity levels and lowering body temperature during times of environmental stress.

The difference between torpor and hibernation is their nature. Torpor is an involuntary stage of sleep in some animals, which lasts for a short period of time, while hibernation is a voluntary stage of sleep in some animals, which lasts for a longer period of time.

CONTENTS

1. Overview and Key Difference
2. What is Torpor 
3. What is Hibernation
4. Similarities – Torpor and Hibernation
5. Torpor vs Hibernation in Tabular Form
6. Summary – Torpor and Hibernation
7.  FAQ – Torpor and Hibernation

What is Torpor?

Torpor is a state of decreased physiological activity in some animals. It is usually marked by a reduced body temperature and metabolic rate. It is also known as temporary hibernation since it lasts for a few hours during the daytime. This process is involuntary, and both food availability and outside temperature influence torpor.

Torpor is generally an animal’s response to becoming too cold, resulting in a state of reduced activity. This process can be somewhat dangerous in birds, as metabolic functions slow down in torpid birds, making them more vulnerable to predators. Additionally, animals that undergo torpor include birds (such as tiny hummingbirds, notably Cypselomorphae) and some mammals, such as marsupial species, rodent species (like mice), and bats.

What is Hibernation?

Hibernation is a state of minimal physiological activity and metabolic depression seen in some animal species. It is a seasonal heterothermy. Hibernation is characterized by low body temperature, slow breathing, heart rate, and low metabolic rate. Hibernation is a voluntary process and mostly occurs in the winter months.

Hibernation helps to conserve energy and occurs when food is not available. Endothermic animals naturally reduce their metabolic rate to conserve energy, thereby lowering their body temperature. Hibernation can last for a few hours, weeks, or months. Furthermore, hibernation can be observed in animals such as rodents, black bears, bats, groundhogs, hedgehogs, snails, bumblebees, snakes, flat-tailed dwarf lemurs, wood frogs, common poorwills, skunks, and box turtles.

Similarities Between Torpor and Hibernation

1. Torpor and hibernation are both states of decreased physiological activity in some animals.
2. Both strategies occur due to scarcity of food and unfavorable outside body temperature.
3. Both strategies can be seen in mammals.
4. Moreover, these strategies occur in winter.
5. This kind of strategy saves the lives of animals.

Comparing the Difference Between Torpor and Hibernation

Definition

1. Torpor is a state of involuntary decreased physiological activity in some animal species.
2. Hibernation is a state of voluntary decreased physiological activity and metabolic depression in some animal species.

Lasts for

1. Torpor lasts for a few hours or weeks during day time.
2. Hibernation lasts for a few hours, weeks, or months.

Risks

1. Hibernating animals are at a high risk of getting parasite infections.
2. Torpid birds are vulnerable to predators more easily.

Examples

1. Birds (tiny hummingbirds, notably Cypselomorphae) and some mammals such as marsupial species, rodent species (mice), and bats are examples of animals that hibernate.
2. Rodents, black bears, bats, groundhogs, hedgehogs, snails, bumblebees, snakes, flat-tailed dwarf lemurs, wood frogs, common poorwills, skunks, and box turtles are examples of animals that experience torpor.

The infographic below presents the differences between torpor and hibernation in tabular form for side-by-side comparison.

Summary – Torpor vs Hibernation

Torpor and hibernation are both states of decreased physiological activity in some animals. Both strategies occur due to scarcity of food and unfavorable outside temperatures. However, torpor is an involuntary stage of decreased physiological activity in some animals, which lasts for a shorter period of time. On the other hand, hibernation is a voluntary stage of decreased physiological activity in some animals, which lasts for a longer period of time. Thus, this summarizes the difference between torpor and hibernation.

FAQ: Torpor and Hibernation

1. What does torpor mean?

• In torpor is a state of mental and motor inactivity with partial or total insensibility (involuntary). It is an extreme sluggishness or stagnation of metabolic function that lasts for a shorter duration.

2. Is torpor a type of dormancy?

• Yes, torpor is a type of dormancy. It is a temporary state of reduced physiological activity in response to adverse conditions, such as low food availability or cold temperatures. During torpor, animals conserve energy by lowering their metabolic rate and body temperature.

3. What are examples of torpor?

• Normally, mammals, birds, and some marsupials undergo torpor. Some specific examples are the California pocket mouse, kangaroo mouse, white-footed mouse, tiny hummingbirds, big brown bats, Richardson’s ground squirrel, and fat-tailed Dunnarts.

4. What are examples of hibernation?

• One of the most iconic examples of hibernation is observed in bears, particularly black bears and brown bears. As winter approaches and food becomes scarce, bears retreat to their dens and enter a state of hibernation. Another well-known hibernator is the European hedgehog. In colder regions, hedgehogs enter hibernation to conserve energy and survive the winter months when food sources are limited.

5. Can a human hibernate?

• While humans typically cannot hibernate, scientists are actively exploring methods to induce a hibernation-like state in humans for extended periods. This could prove invaluable for astronauts during deep space exploration, as it would reduce the consumption of food and oxygen, potentially leading to successful long-duration missions.

Reference:

1. Dowd, Bill. “How Does Torpor Differ from Hibernation?” Skedaddle Humane Wildlife Control.
2. “Hibernation.” Encyclopædia Britannica, Encyclopædia Britannica, inc.

Image Courtesy:

1. “Hibernation” By Jay Turner (CC BY-NC-ND 2.0 DEED) via Flickr
2. “Dormice” By Kentish Plumber (CC BY-NC-ND 2.0 DEED) via Flickr