Biology / Unit 10 Bio 2269 short lesson, about 20 seconds
Arthropod Defining Traits
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The idea
An arthropod has a segmented body, a rigid chitin exoskeleton, and paired, jointed appendages, a plan behind more species than any phylum.
In practice
A crab's jointed legs and hardened exoskeleton let it support its weight and move precisely on land or seafloor.
Where people slip
An exoskeleton must be molted to allow growth, per Bio 2263 — arthropods cannot enlarge a rigid covering as they grow.
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