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Worksheet: warm-blooded and cold-blooded animals (with answer key)
Printable worksheet: sort Indonesian animals into endotherms or ectotherms, explain how each controls its temperature, and check the key.
This worksheet is ready to print: use your browser’s print command (Ctrl+P or ⌘P). The answer key for teachers is at the end and starts on a new sheet when printed. The full lesson is on the lesson page. Warm-blooded and cold-blooded animals: endotherms and ectotherms
Enrichment
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Learning goals
- Students can tell endotherms and ectotherms apart by the source of their body heat.
- Students can explain, with examples, why "cold-blooded" is a misleading term.
- Students can explain how ectotherms and endotherms control their body temperature, using Indonesian animals as examples.
- Students can use the terms endotherm, ectotherm, homeotherm and poikilotherm correctly.
Short reading
Warm-blooded animals (endotherms) make their body heat from their own metabolism; examples are mammals and birds. Cold-blooded animals (ectotherms) mainly use heat from their surroundings; examples are fish, amphibians, reptiles and most invertebrates. An ectotherm's blood is not always cold, and ectotherms can still control their temperature through behaviour.
- Endotherms (warm-blooded animals) make their own body heat by metabolism; mammals and birds are endotherms.
- Ectotherms (cold-blooded animals) mainly use heat from their surroundings; fish, amphibians, reptiles and most invertebrates are ectotherms.
- "Cold-blooded" is a misleading term, because the blood of a basking snake or Komodo dragon can be warm.
- Ectotherms control their body temperature through behaviour: basking, seeking shade, soaking in water or retreating into burrows.
- Endotherms need more food than ectotherms of a similar size, because making body heat takes energy.
- There are exceptions, such as the leatherback turtle, which stays warmer than the sea, and the echidna, which has a low body temperature.
Activity 1
Write whether each animal is an endotherm (warm-blooded) or an ectotherm (cold-blooded), then give one way it gets or keeps its body heat.
| No | Animal | Your answer |
|---|---|---|
| 1 | Sumatran orangutan | |
| 2 | Barn owl | |
| 3 | Dugong | |
| 4 | Komodo dragon | |
| 5 | Saltwater crocodile | |
| 6 | Whale shark | |
| 7 | Asian common toad | |
| 8 | Leatherback turtle | |
| 9 | Western long-beaked echidna | |
| 10 | Asian honey bee | |
| 11 | Human |
Activity 2
- What is the main difference between endotherms and ectotherms?
- Why is "cold-blooded" a misleading term? Give one example.
- Name two ways crocodiles control their body temperature.
- Why do endotherms need to eat a lot?
- Name one animal that does not fit the warm-blooded and cold-blooded groups, and explain.
Reflection
What do you feel and do when it is very hot or very cold? Is that more like an endotherm or an ectotherm?
Which fact most changed what you thought about cold-blooded animals?
Why should we only watch geckos, lizards or snakes from a distance?
Answer key (for teachers)
Activity 1
- Sumatran orangutan: Endotherm; heat from metabolism, and hair helps keep it in
- Barn owl: Endotherm; makes its own heat and keeps a fairly steady temperature
- Dugong: Endotherm; a sea mammal that makes its own heat
- Komodo dragon: Ectotherm; basks, and goes into a burrow when it is very hot
- Saltwater crocodile: Ectotherm; soaks in water when hot, basks on rocks when cold
- Whale shark: Ectotherm; its heat comes mainly from its surroundings
- Asian common toad: Ectotherm; controls its temperature through behaviour, such as choosing where to be
- Leatherback turtle: Ectotherm (reptile), but a fat layer and heat-exchanging vessels keep it warmer than the water
- Western long-beaked echidna: Endotherm (mammal), but with a low (28–35 °C), less steady body temperature
- Asian honey bee: Ectotherm (poikilotherm) as an individual, but it can make heat, for example in a hot ball against hornets
- Human: Endotherm; sweats when hot, shivers when cold
Activity 2
- What is the main difference between endotherms and ectotherms? Where their body heat comes from. Endotherms make heat by metabolism; ectotherms mainly use heat from their surroundings.
- Why is "cold-blooded" a misleading term? Give one example. Because an ectotherm’s body can become warm. A basking snake is one example; Komodo dragons also regulate temperature by moving between exposed places and burrows.
- Name two ways crocodiles control their body temperature. Soaking in water when hot, and basking on rocks when cold. Crocodiles also often gape, which slows the heating of the head.
- Why do endotherms need to eat a lot? Because making and controlling their own body heat takes a lot of energy, and that energy comes from food.
- Name one animal that does not fit the warm-blooded and cold-blooded groups, and explain. Examples: the leatherback turtle (a reptile warmer than the sea), the opah (a fish with a warm body) or the echidna (a mammal at 28–35 °C).
Sources: Keputusan Kepala BSKAP No. 046/H/KR/2025 ↗ · Animal Diversity Web (University of Michigan): glossary entry "endothermic", Pongo abelii account ↗ · Ilmu Pengetahuan Alam untuk SMP/MTs Kelas IX (Edisi Revisi 2025), Bab 1 ↗ · Animal Diversity Web (University of Michigan): glossary entry "ectothermic", Crocodylus porosus account ↗ · Animal Diversity Web: Felis catus (Other Physical Features) ↗ · Animal Diversity Web: Hemidactylus frenatus (Other Physical Features) ↗ · University of North Georgia, Tumbling Creek project: Reptiles & Amphibians ↗ · Rice University, OpenStax — Biology 2e, 33.3 Homeostasis ↗ · Lewicka et al. (2024), Biological Significance of the Komodo Dragon's Tail, Animals (PMC) ↗ · Ariefiandy et al. (2013), Can camera traps monitor Komodo dragons a large ectothermic predator? PLoS ONE (PMC) ↗ · KBBI VI Daring (Badan Bahasa, Kemendikdasmen): endoterm ↗ · KBBI VI Daring (Badan Bahasa, Kemendikdasmen): homoiterm ↗
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