Britannica Sources used in this answer

Why did Jean-Baptiste Lamarck separate spiders and crustaceans from insects?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

blue wildebeests — Zoology Blue wildebeests (*Connochaetes taurinus*) drinking at the water's edge, Masai Mara, Kenya.

In the history of zoology, Jean-Baptiste Lamarck is recognized as an influential taxonomist who sought to create a more natural system of classification for the animal kingdom.12

Lamarck separated spiders and crustaceans from insects by establishing them as distinct classes. This move was part of his broader effort to organize animals into a system that reflected their "natural affinity" and increasing levels of biological complexity. By distinguishing these groups, Lamarck moved away from older, less precise classifications, helping to refine the understanding of arthropod diversity.12

While his specific evolutionary mechanism—the inheritance of acquired characters—was later discredited, his work as a systematist was foundational in moving biology toward a more empirical and structured approach to classifying life.12