You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Brain

Context:
There are several invertebrate species whose brains have been studied intensively because they have properties that make them convenient for experimental work:

Question:
Which brains are easier to work on, vertebrates or invertebrates?

invertebrate