deuterostone
Deuterostome is a term used in biology to describe a group of animals that exhibit a specific pattern of embryonic development. This pattern is characterized by the formation of the anus before the mouth during gastrulation, the process by which a single-layered embryo develops into a three-layered structure. This is in contrast to protostomes, where the mouth develops first. Deuterostomes include a diverse range of animals, such as echinoderms (starfish, sea urchins), hemichordates (acorn worms), and chordates (vertebrates, tunicates).
The term "deuterostome" was coined by Ernst Haeckel in the late 19th century. The classification is based
Deuterostomes are further divided into two main groups: echinoderms and chordates. Echinoderms are characterized by their
The deuterostome lineage is believed to have diverged from the protostome lineage around 550 million years