Cool blood, warm blood

The idea

Separating oxygenated and deoxygenated blood gives an efficient oxygen supply, needed by birds and mammals that use energy to keep body temperature; amphibians and many reptiles, whose body temperature follows the environment, have three-chambered hearts tolerating some mixing.

Energy and temperature

Birds and mammals constantly use energy to keep their body temperature steady.

What kind of oxygen supply do you think such animals need?

• A very efficient one
• A very poor one
• None

Mix or no mix?

Sort each item: is the blood kept separate, or is some mixing tolerated?

A matter of energy

Separating the oxygen-rich and carbon dioxide-rich blood gives a highly efficient supply of oxygen. That is useful to birds and mammals, which constantly use energy to keep their body temperature. Animals whose body temperature depends on the environment, like amphibians and many reptiles, have three-chambered hearts and tolerate some mixing.

Separating oxygenated and deoxygenated blood gives an efficient oxygen supply, needed by birds and mammals that use energy to keep body temperature; amphibians and many reptiles, whose body temperature follows the environment, have three-chambered hearts tolerating some mixing.

Notes

Separating oxygen-rich and CO₂-rich blood gives efficient oxygen supply for birds and mammals (which use energy for body temperature); amphibians and many reptiles have three-chambered hearts and tolerate some mixing.

Check yourself

Why is separating oxygenated and de-oxygenated blood useful for birds and mammals?

Which animals have three-chambered hearts?

How many chambers does the heart of an amphibian have?

Answer: 3

The book says amphibians and many reptiles have three-chambered hearts.

In amphibians and many reptiles, what does body temperature depend on?

• It gives a highly efficient supply of oxygen for their high energy needs — correct. Yes!
• It makes their body temperature follow the environment. Birds and mammals constantly use energy to maintain their body temperature.
• It lets some of the blood mix. Separation keeps the two kinds of blood from mixing.
• Birds and mammals. Birds and mammals keep oxygenated and de-oxygenated blood separate.
• Amphibians and many reptiles — correct. Yes!
• Fishes. Fishes have only two chambers in their hearts.
• The energy they constantly use to keep warm. That describes birds and mammals.
• The separation of the two kinds of blood. The book says their body temperature depends on the temperature in the environment.
• The temperature of the environment — correct. Yes!