Echinoderms Are Descended from Bilaterians, but Many Members of the Group

question 115

Multiple Choice

Echinoderms are descended from bilaterians, but many members of the group lack a brain, have no specialized sense organs, and have radial nerves that extend down each "arm" from a central nerve ring that surrounds the gut. What was a likely selective pressure in the evolution of this type of nervous system?

• A)ability to move forward
• B)role as a predator in the ecosystem
• C)multicellularity
• D)possession of an endoskeleton of calcium carbonate
• E)None of the other answer options is correct.

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