Animal responses to changes in temperature

It’s a really hot day and Maria is taking Diva for a walk in the park. Look Maria, there’s some shade! - Finally! This is so much better. But what if Diva is still too warm? Don’t worry!

You are both in the shade and that helps you keep cool. Also, look at how Diva is breathing! Her tongue is hanging out, and she is breathing deeply and quickly. - How does that help her? Well, when Diva’s tongue is hanging out, the saliva evaporates faster, and this cools her body down! It’s called panting and it’s similar to what happens when your skin sweats to keep you cool.

Unlike humans, animals don’t usually live in houses that would protect them from the heat or the cold. Also, they don’t wear clothes like we do, which would help them to keep warm. Animals have other ways - or mechanisms, that they use to stay warm, or cool down. Some of them happen naturally in the body and animals can’t control them. They are called physiological mechanisms.

But sometimes animals change what they are doing - their behaviour, to warm up or cool down. These are called behavioural mechanisms. The mechanisms seem very different, but are actually very connected and depend on each other! When goats feel cold, their muscles start contracting and relaxing - they start shivering. This creates heat that is spread around the body.

The goats can’t control this, it is a physiological reaction. Now the goats are warmer, but not warm enough. So they change their behaviour! They move closer together to keep each other warm. Shivering is one of many responses to changes in temperature.

When animals are in a warm environment, each hair lies flat on their skin. Their bodies cool faster this way. But when it gets cold, each hair stands up straight! This traps air close to the skin, and creates a layer that keeps the animals warm. Something else happens in the body when animals need to get rid of heat: Their blood vessels get wider!

Blood is warm. So when the blood vessels get wider, more blood flows closer to the skin, and the heat can pass out more easily. This process is called vasodilation. But if an animal needs to keep the heat inside, the blood vessels get smaller. There is more space between them and the surface of the skin, and more heat is saved.

This process is vasoconstriction. Now we know what happens automatically in the bodies of animals when their surroundings get hotter or colder. But animals also change their behaviour - like the goats that moved closer together! It’s late autumn in this forest. This brown bear escapes the extreme cold by crawling into a hole - a den.

There it sleeps. It doesn’t eat and it doesn’t come out again until spring. This is called hibernation. Birds escape from the cold in a different way. They fly far away, to warmer places... ...like this savanna!

The birds move - migrate - here to be warm. Even though some animals living here find it too hot… ...like frogs! They are especially sensitive to heat. When it gets too hot, they will become inactive, eating nothing at all, for longer periods of time. This process is called aestivation.

It’s very similar to the bear’s hibernation, but it happens in a hot environment. Maria, Diva is running away! - I’ve just ‘observed’ another way that animals change temperature!