Biology / Unit 10 Bio 2261 short lesson, about 20 seconds
Annelid Segmentation
Captions available
The idea
An annelid's body divides into repeating segments, each often carrying its own muscles, nerves, and excretory structures, an arrangement supporting precise, localized movement.
In practice
An earthworm's segmented muscles contract in coordinated waves, letting sections of its body move independently as it burrows.
Where people slip
Annelid segmentation evolved independently from the similar-looking segmentation in arthropods, per molecular evidence placing the two phyla in separate clades.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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