You experiment with a live earthworm and notice the following results: - With an intact earthworm,when you "poke" a segment,it contracts.- When you cut off the first segments containing the brain,the remaining worm still crawls.- When you cut the nerve in each septal wall,contractions continue.- If you cut the body wall,leaving the nerve cord intact,crawling still continues.- When you cut both the body wall nerve and the nerve cord,there are no longer any coordinated contractions.What is a reasonable conclusion?
A)An earthworm's brain controls crawling.
B)The ventral nerve cord controls all contractions.
C)Mechanical stimulation of each segment triggers contractions.
D)Earthworms use ventral nerve cord to coordinate contractions along the length of the worm and mechanical stimulation of each segment to triggers segmental responses during crawling.
E)None of the choices is correct.

Question

Quizplus · Accepted Answer

The experiments show that the brain is not necessary for the worm to crawl, contractions continue even when the nerve in each septal wall is cut, and mechanical stimulation of each segment triggers contractions. Therefore, we can conclude that the ventral nerve cord is responsible for coordinating contractions along the length of the worm, while mechanical stimulation of each segment triggers segmental responses during crawling. Cutting both the body wall nerve and the nerve cord results in no coordinated contractions, indicating that both are necessary for coordination.

You Experiment with a Live Earthworm and Notice the Following