We have identified about 1.8 million species so far, but our knowledge of Earth’s total biodiversity is scant. Some researchers, especially those who work with tropical species and insects, believe the estimates of 3 to 11 million species are far too low; there may well be 5 million insect species alone. Of the species we have identified, insects far outnumber any other group of organisms. In fact, vertebrates (the group to which humans belong) likely make up only 1% of all creatures on Earth.