The term “invertebrates” was coined by the French zoologist and botanist Jean-Baptiste de Lamarck in the early 19th century. He was the first to address the classification of the then so-called “lower animals” and divided them into different categories and classes.
Invertebrates are not closely related to each other. The term is used to distinguish them from vertebrate animals. All animals without a spine are invertebrates. Thus, the majority of all known animal species are invertebrates.