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 …

2017年4月5日 · Protostomes are a clade of animals that undergo protostomy during their embryonic development. The protostomes, together with the Deuterostomes and the …

Protostomes are primitive invertebrates while deuterostomes include chordates and echinoderms. This division is helpful in understanding the relationships between different groups of animals.

The term Protostomia (from the Greek "proto," meaning first, and "stoma," meaning mouth) was coined by the biologist Karl Grobben in 1908. It distinguishes a group of invertebrate animals …

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 …

The meaning of PROTOSTOMIA is animals in which the definitive mouth develops directly from the blastopore (as most worms, bryozoans, brachiopods, mollusks, and arthropods).