Biology / Unit 10 Bio 2281 short lesson, about 20 seconds
Phylum Hemichordata
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The idea
Hemichordates, including acorn worms, are marine deuterostomes bearing pharyngeal slits, a trait shared with chordates, and a dorsal nerve cord that, unlike a chordate's, lacks a neural tube.
In practice
An acorn worm's pharyngeal slits filter water for food particles, a trait chordates share through deuterostome common ancestry.
Where people slip
Shared pharyngeal slits reflect deuterostome common ancestry, not a claim that hemichordates are themselves chordates.
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