When Captain Olimar sees a creature or feature of the planet's biology, he jots down some notes. His notes, unlike Louie's notes, are very informative and provide a lot of detail. Olimar speculates quite a lot, though that is natural due to the sheer strangeness of the life forms on the planet. He also appears to be quite the biologist, if one assumes that all of his notes are his honest opinions.
Example
“The males of this species are purple and black creatures with tapered mouths, while the females are lighter in color and lack an armored exoskeleton. As with most mandiblards, these creatures have regressed to the point where they have lost both legs and wings. They can be seen crawling around on the ground and are believed to feed on the vegetable extracts from the congealed fluids of expired Pikmin.”