Main Difference – Ectotherms vs Endotherms
Ectotherms and endotherms are two types of animals that use different modes of temperature regulation in the body. Ectotherms are also known as cold-blooded animals while endotherms are known as warm-blooded animals. The main difference between ectotherms and endotherms is that ectotherms rely on external sources such as sunlight to regulate their body temperature whereas endotherms regulate their body temperatures by maintaining the functions of the body. Invertebrates, fish, amphibians, and reptiles are ectotherms while birds and mammals are endotherms.
Key Areas Covered
1. What are Ectotherms
– Definition, Characteristics, Examples
2. What are Endotherms
– Definition, Characteristics, Examples
3. What are the Similarities Between Ectotherms and Endotherms
– Outline of Common Features
4. What is the Difference Between Ectotherms and Endotherms
– Comparison of Key Differences
Key Terms: Ectotherms, Endotherms, Feathers, Hair, Hibernation, Optimal Temperature, Vertebrate Animals
What are Ectotherms
Ectotherms are cold-blooded animals that depend on external sources of body heat such as sunlight. This means these animals cannot control their body temperature through physiological conditions. Invertebrates, fish, amphibians, and reptiles are ectotherms. Ectotherms live in habitats with ambient temperatures such as oceans. The ectotherms that live on the land use basking in the sun and cooling off in shady places to regulate the body temperature. Turtles basking in the sun are shown in figure 1.
Some insects vibrate their muscles attached to their wings to generate heat rather than flapping the wings. As ectotherms depend on the environmental temperature, they are sluggish early morning and during the night. During the winter, most ectotherms enter torpor, a short-term hibernation that lasts for a few hours. Hibernation is a state with slow metabolism in animals. However, ectotherms can become hibernates that live inactively for seasons. As an example, some ectotherms such as burrowing frog lives as a hibernate for years. The metabolic activity of the hibernate state is about 2% of the metabolic rating in the active rate.
What are Endotherms
Endotherms (warm-blooded) are animals that are capable of internal generation of heat. This means endotherms generate their own heat to maintain body temperature at an optimal value. Heat is generated in the internal organs. Two third of the heat is generated in the thorax and 15% of the heat is generated by the brain. Birds and mammals are the two types of endotherms. These animals maintain their body temperature independently from the temperature of the surroundings. A yak that lives in altitude under low-temperature conditions is shown in figure 2.
As endotherms use metabolic reactions for the generation of heat, they have a higher metabolic rate than ectotherms. They consume more sugar and fats for survival under cold temperatures. The body of endotherms is covered with hair or fur to protect against cold temperature. Endotherms shiver in the cold to generate heat from the muscles. Birds have feathers to conserve heat in the cold temperatures.
Similarities Between Ectotherms and Endotherms
- Ectotherms and endotherms are two types of animals.
- Both ectotherms and endotherms have a closed circulatory system in which blood circulates through the heart and blood vessels.
Difference Between Ectotherms and Endotherms
Ectotherms: Ectotherms are animals that depend on external sources of body heat.
Endotherms: Endotherms are animals that are capable of internal generation of heat.
Ectotherms: Ectotherms are also known as cold-blooded animals.
Endotherms: Endotherms are also known as warm-blooded animals.
Types of Animals
Ectotherms: Invertebrates, fish, amphibians, and reptiles are ectotherms.
Endotherms: Birds and mammals are endotherms.
Mode of Temperature Regulation
Ectotherms: Ectotherms regulate their body temperature with the use of external temperature sources.
Endotherms: Endotherms regulate their body temperature by maintaining their functions of the body.
Body Temperature Variation
Ectotherms: Body temperature varies over time.
Endotherms: Endotherms have a constant body temperature that depends on the type of endotherm.
Effect of the Surrounding Temperature
Ectotherms: The body temperature of ectotherms varies with the surrounding temperature.
Endotherms: The body temperature of endotherms does not vary with the surrounding temperature.
Ectotherms: Ectotherms are less active in cold temperatures.
Endotherms: Endotherms are active over a wide range of environmental conditions.
Ectotherms: The geological distribution of ectotherms is less.
Endotherms: The geological distribution of endotherms is high.
Ectotherms: Ectotherms require less food.
Endotherms: Endotherms require more food than ectotherms.
Ectotherms: Ectotherms have low metabolic rates.
Endotherms: Endotherms have high metabolic rates.
Ectotherms and endotherms are two types of animals. Ectotherms are cold-blooded animals that use external sources of temperature to regulate their body temperature such as sunlight. However, endotherms regulate their body temperature by maintaining the metabolism of the body. Therefore, the main difference between ectotherms and endotherms is their modes of temperature regulation.
1. Kennedy, Jennifer. “Why Reptiles Aren’t Actually Cold-Blooded.” ThoughtCo, .
2. “Endotherm.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 28 Aug. 2017, .
1. “Basking turtles” By Oxlamb – Own work (Public Domain) via
2. “Bos grunniens at Yundrok Yumtso Lake” By Dennis Jarvis via