Animal Groups — Answer Key
Part A: Multiple Choice
Circle the letter of the best answer.
1. A whale lives in the ocean. Why is a whale a mammal and not a fish?
A) It is very big
B) It breathes air and feeds its baby milk
C) It swims in the water
D) It has a tail
A whale is a mammal — not a fish — because it breathes air with lungs and feeds its baby milk. These two traits define all mammals, even those that live in the ocean.
2. Which feature do ALL birds share?
A) They can all fly
B) They all live in trees
C) They all have feathers
D) They all eat seeds
All birds have feathers — this is the one feature every bird shares. Not all birds can fly, live in trees, or eat seeds, but every bird has feathers.
3. What does it mean when an animal is cold-blooded?
A) It lives in a cold place
B) Its body temperature changes with the environment
C) It does not have blood
D) It is always freezing
Cold-blooded means an animal's body temperature changes with its surroundings. Reptiles and fish are cold-blooded and must use the sun or shade to regulate their temperature.
4. An animal has a backbone inside its body. What is this animal called?
A) An invertebrate
B) An insect
C) A vertebrate
D) A plant
An animal with a backbone is called a vertebrate. Mammals, birds, reptiles, fish, and amphibians are all vertebrates.
Part B: Fill in the Blank
Write the missing word on the line.
1. Animals with a backbone are called vertebrates.
Animals with a backbone are called vertebrates. The backbone, or spine, supports the animal's body and protects the spinal cord.
2. Insects do not have a backbone, so they are invertebrates.
Insects do not have a backbone, so they are invertebrates. Invertebrates make up more than 95% of all animal species on Earth.
3. Mammals and birds are warm -blooded animals.
Mammals and birds are warm-blooded animals. Their bodies produce their own heat and maintain a steady internal temperature.
4. Reptiles and fish are cold -blooded animals.
Reptiles and fish are cold-blooded animals. Their body temperature depends on the temperature of their surroundings.
5. A penguin cannot fly, but it is still a bird because it has feathers.
A penguin cannot fly, but it is still a bird because it has feathers and lays eggs. Having feathers is the defining trait of all birds.