Protostomia (/ ˌproʊtəˈstoʊmi.ə /) is the clade of animals once thought to be characterized by the formation of the organism's mouth before its anus during embryonic development.

Protostomia, group of animals—including the arthropods (e.g., insects, crabs), mollusks (clams, snails), annelid worms, and some other groups—classified together largely on the basis of embryological …

Apr 28, 2017 · Protostomes are a clade of animals that undergo protostomy during their embryonic development. The protostomes, together with the Deuterostomes and the Xenacoelomorpha, make …

Jul 23, 2025 · Protostomes develop their mouths before their anus, while deuterostomes develop their anus first, followed by the mouth. Additionally, protostomes have a solid and ventral nerve cord, …

Aug 26, 2025 · Protostomes are a major classification within the animal kingdom, encompassing many creatures. They are bilateral animals. Along with deuterostomes, this classification helps scientists …

Protostomes are animals whose blastopore (initiated by gastrulation) becomes the mouth of the future digestive system. This is called protostomy or “first mouth.” In protostomy, solid groups of cells split …

Animals in which the blastopore becomes the mouth are called protostomes; those in which the mouth develops after the anus are called deuterostomes (from the Greek "deutero," meaning second, and …

The meaning of PROTOSTOME is any of a major group (Protostomia) of bilateral metazoan animals (such as mollusks, annelids, and arthropods) characterized in typical forms by determinate and spiral …

May 21, 2024 · Unsurprisingly, protostomes encompass the world's simplest animals, including the earliest bilateral animals to appear in the fossil record, such as arthropods and molluscs.

Jan 6, 2026 · Three main clades of protostomes are now recognized: Ecdysozoa; Lophotrochozoa; and Platyzoa. An animal in which the mouth develops from the opening (blastopore) of the embryonic …