Biology / Unit 10 Bio 2287 short lesson, about 20 seconds
Chordate Defining Traits
Captions available
The idea
A chordate embryo develops five traits at some stage: a notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, and endostyle (or its thyroid derivative).
In practice
A human embryo develops all five traits, though the notochord, tail, and endostyle are later lost or transformed.
Where people slip
Losing a trait later does not remove an organism from the phylum — the criterion applies at some point.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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