I want to know the answer to the following question:
Why are  the fruit fly and the nematode the most intensively studied metazoan model organisms?
All the background I'm provided with is that "Because of the great diversity found in animals, it is more economical for scientists to study a small number of chosen species so that connections can be drawn from their work and conclusions extrapolated about how animals function in general.". Is that enough to answer the question?
Answer: no