deuterostome

Deuterostomes are a major group within the animal kingdom, classified as a superphylum. The name "deuterostome" means "mouth second," which refers to a key aspect of their embryonic development. In deuterostomes, the first opening that forms during gastrulation, known as the blastopore, becomes the anus. A second opening then develops to form the mouth. This developmental pattern contrasts with that of protostomes, where the blastopore typically becomes the mouth.

This group is characterized by several other shared features. They generally exhibit radial cleavage in their early cell divisions, where the cells are arranged directly above one another. The coelom, or body cavity, forms through a process called enterocoely, where mesoderm pockets pinch off from the developing gut. Deuterostomes are also deuterostomes are also considered to be enterocoelomates.

The deuterostome group includes three principal phyla: Chordata, Echinodermata, and Hemichordata. The Chordata phylum is particularly significant as it contains all vertebrate animals, including fish, amphibians, reptiles, birds, and mammals. Echinoderms are marine animals like starfish and sea urchins, while hemichordates include acorn worms. This evolutionary relationship highlights the connection between vertebrates and these seemingly very different invertebrate groups. The study of deuterostomes provides crucial insights into the evolutionary history of the animal kingdom, especially the origins of vertebrates.