Animal Basics
An organism is multicellular, consumes food, and has specialized cells but does not move as an adult. Why is it still classified as an animal?
Movement not required
Two animals differ only in symmetry (radial vs bilateral). What does this allow scientists to do?
Classify groups
An animal has stinging cells and radial symmetry. Why is it NOT a mollusk?
No Shell/ Cnidarians/ Jellyfish
An animal has a backbone and living tissue skeleton. Why is it NOT an arthropod?
No exoskeleton
Why can symmetry be used for classification but movement cannot?
Always present vs variable
Why is being eukaryotic NOT useful for classifying animals into groups?
All animals share it
An animal has a hard outer covering but no internal bones. What TWO traits lead to its classification?
No backbone + exoskeleton
What group has soft bodies and often shells?
Mollusks
A bird and a reptile both lay eggs. What key difference separates them?
Endothermy
Why can an organism still be an animal if it does not move as an adult?
Movement not required
An animal has tissues, organs, and systems. What does this suggest about its complexity compared to a sponge?
More complex
An organism has one digestive opening. What can you conclude about how it processes food?
Incomplete gut
One-way limited
What group has jointed appendages and an exoskeleton?
Arthropods
Amphibians and reptiles both have four limbs. What better trait distinguishes them?
Metamorphosis / skin
A fish has gills instead of lungs. What does this reveal about its environment?
Water
Why is “having a backbone” a stronger classification trait than “having fins”?
Defines major group
What type of symmetry has no mirror-image halves?
Asymmetry
A snail and a crab both have protection. Why are they in different groups?
Shell vs joints
A reptile and bird both breathe air. Why are they still classified differently?
Body systems differ
An unknown animal has radial symmetry, no head, and simple structure. Which group and why?
Cnidarian/simple traits
A student says “if it doesn’t move as an adult, it’s not an animal.” Explain why this is incorrect using classification traits.
Other traits define animals
A scientist must choose between symmetry and habitat to classify animals. Which is better and why?
Symmetry more reliable
What group has spiny skin?
Echinoderms
A kangaroo, dog, and platypus are placed in different mammal groups because of this key difference in reproduction.
How their young develop
A lizard warms in the sun while a bird stays active. What does this show?
Ectotherm vs endotherm