Question

the figure shows a simple worm. bilateral symmetry and a highly branched gastrovascular cavity all suggest that the worm is a(n) _______.

options: flatworm, annelid, chordate, mollusk

Explanation:

Flatworms (Platyhelminthes) have bilateral symmetry. They also have a gastrovascular cavity which is highly branched. Annelids have a complete digestive system (not just a gastrovascular cavity). Chordates have a notochord, dorsal - hollow nerve cord etc. Mollusks have a mantle, visceral mass etc. and their body plan is different from the description given.

Answer:

flatworm