From Sponge to Vertebrate: A Narrative Review of the Animal Phyla, from Linnaeus's Inventory to the Molecular Tree of Life
Year: 2026
Type: review
Abstract: The animal phyla are biology's largest inventory: some thirty-odd body plans---from the sponge's loose federation of cells to the chordate's notochord and nerve cord---within which every animal, from coral to bird, is organized. This article presents a narrative review of the primary literature that built, and then rebuilt, that inventory. The synthesis is organized around three themes: the classical inventory, in which Linnaeus's system, Hennig's phylogenetic systematics, and the great invertebrate syntheses of Barnes and of Brusca and Brusca catalogued the phyla with their classes and orders; the new phylogeny, in which Adoutte's and Halanych's molecular syntheses and Dunn's phylogenomic sampling resolved the deep splits---Bilateria, deuterostomes, ecdysozoans, lophotrochozoans---and Nielsen's comparative anatomy gave them morphological sense; and the origin of the phyla, in which Valentine's origin of phyla, Gould's Burgess Shale, Erwin's Cambrian conundrum, and Telford and Littlewood's synthesis asked when, how, and why the body plans were fixed. It is concluded that the phyla are both inventory and history: morphological grades of a single radiation whose deep branching the molecular tree now fixes, and whose classes and orders remain the working currency of zoology.
Authors: Revista, Zen, BIOLOGY, 10
Institution: Faculdades Guarulhos
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7204751220