Most organisms thrive at an optimal body temperature. In this lesson, you will learn about how some animals rely on external sources to raise or lower their body temperature because they are not able to maintain it through internal processes.
What Are Ectotherms?
When you get cold, you probably warm up by putting on some extra layers or going to a warmer place, such as the inside of a building. Changing your environment helps warm you up, but your body is also at work because it stays pretty much the same temperature no matter what the temperature is around you.
Your body regulates its own temperature because your cellular functions and processes work the best when you are approximately 98.6 ° F. Because your body is able to maintain a specific temperature despite the surrounding conditions, you are an endotherm.
There are many organisms that are not able to maintain their own body temperature, and these are called ectotherms. Ectotherms depend on the external environment to either warm or cool themselves because their body does not do this for them. Like your body though, the cellular processes of ectotherms also function best at certain temperatures, so ectotherms find various ways to make sure they do not get too hot or too cold.
One way that ectotherms may increase their body temperature is to seek out heat sources. Reptiles are a great example of this. Snakes, turtles, lizards, and alligators are all examples of animals that use the sun to warm themselves.
You may have even seen this, as many of these animals lie on hot pavement during the day or come out of the water to bask on logs or small islands. Likewise, if they get too warm, they may seek out shade to cool off.
Some ectotherms regulate their body temperature by living in environments that have fairly constant conditions. Many marine invertebrates live in aquatic conditions that fluctuate very little, and therefore do not need to seek out heat or cooling sources because their body temperature matches that of the surrounding water.Some ectotherms will go into a sort of hibernation called torpor if they get too cold.
Torpor essentially shuts down the body so that metabolism either slows down drastically or stops all together. This allows ectotherms to survive cold conditions for extended periods of time. Some endotherms are also able to go into torpor, but this is usually to survive periods of time when food availability is low. Examples of endotherms that utilize torpor are bats, birds, and mice.
Depending on the Environment
Because ectotherms do not internally regulate their own body temperature, they do not need to take in as much food as endotherms. They also generally don’t expend as much energy looking for food, because looking for food is very energy costly, so many ectotherms will wait for food to come to them.While this does not use as much energy as actively looking for food, it may not be very productive either.
Alligators again provide a very good example here, as they are predators that wait for long periods of time for food to come to them, and then quickly act when the time is right.Ectotherms tend to be more sluggish when they’re cold because their metabolism has slowed during these times. Animals that cool down during the night when the sun is not available often need to warm up before they can take on the day.
The sun is like an ectotherm’s morning cup of coffee; they need it to kick start them so that they can start looking for food.
Let’s review:Ectotherms depend on external conditions to regulate their body temperature. This can be beneficial, because less energy is used for metabolic processes, but it can also be costly because they have to wait for their food to come to them.Many ectotherms go into torpor during extended periods of cold because this slows their metabolism and allows them to survive such conditions. Some ectotherms seek out heat sources to increase their body temperature, while others live in environments with nearly constant conditions.