Biology / Unit 10 Bio 2263 short lesson, about 20 seconds
Ecdysozoa Defined: the Molting Cuticle
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The idea
Ecdysozoa groups protostome, per Bio 2225, phyla whose members grow by molting a rigid outer cuticle: nematodes, tardigrades, and arthropods.
In practice
A growing nematode periodically sheds its old cuticle and secretes a larger one underneath, a process called ecdysis.
Where people slip
A rigid cuticle that cannot stretch makes molting necessary for growth in this clade — Lophotrochozoa phyla do not share this constraint.
Your place on the trail
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