Aristotle did not simply record his observations.
His greatest contribution to biology was the creation of a system of classification.
He devised a system of grouping animal species by type that remained the best system for over 2,000 years.
Aristotle’s classification divided the animal kingdom into two groups: those with blood and those without blood. This is basically the same as Swedish scientist Carolus Linnaeus’s classification of vertebrates and invertebrates devised in 1758.
Aristotle divided his blood animals into fishes, reptiles and amphibians, birds, sea mammals, land animals, and humans.
His bloodless classification included the following groups: insects, mollusks, sponges and corals, lobsters and crabs, and octopuses and squid.
With a few changes, these correspond to groups in Linnaeus’s modern classification system.