Helping the Professor

Eighty percent of all living creatures… are females? I guessed. The professor gave me a frown. May I finish? He asked me. Sure, I agreed. But I guessed a second time. Guessing trees. Because they are living, right? The scientist was irritated now. I had apparently ruined his train of thought. He finally spit out that eighty percent of all living things on earth are insects. And trees, I added, knowing I was also right.