Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 


Question: What is a longitudinal, flexible rod located between the digestive tube and the nerve cord?
the notochord
Mesentery. (This is incorrect, the answer is actually mesentery or mesenteries, as it can refer to multiple structures, but