A young girl walking along the beach discovers a sea sponge washed up on the shore. She pokes it with her finger, and the animal
contracts locally in response. Because the sea sponge reacted to her poke, the girl concludes that this animal has a brain. Is this conclusion correct? A) Yes, if an animal responds to any type of touch or sensory signal, the animal must have a brain where such a signal is processed.
B) Yes, sea sponges are known to have brains; however, these structures are relatively simple compared to the brains of vertebrates.
C) No, sea sponges possess paired ganglia that process their responses to touch or environmental changes (much like flatworms).
D) No, sea sponges actually lack any type of nervous system—the reaction the girl observed is the result of a local population of touch-sensitive (non-neuronal) cells.
E) None of the answer options is correct.
