Deuterostomes | |
---|---|
Diversity of deuterostomes | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Clade: | ParaHoxozoa |
Clade: | Bilateria |
Clade: | Nephrozoa |
Superphylum: | Deuterostomia Grobben, 1908 |
Clades | |
Deuterostomes (from Greek: lit. 'mouth second') are bilaterian animals of the superphylum Deuterostomia (/ˌdjuːtərəˈstoʊmi.ə/),[3][4] typically characterized by their anus forming before the mouth during embryonic development. Deuterostomia is further divided into four phyla: Chordata, Echinodermata, Hemichordata, and the extinct Vetulicolia known from Cambrian fossils. The extinct clade Cambroernida is thought to be a member of Deuterostomia.
In deuterostomes, the developing embryo's first opening (the blastopore) becomes the anus and cloaca, while the mouth is formed at a different site later on. This was initially the group's distinguishing characteristic, but deuterostomy has since been discovered among protostomes as well.[5] The deuterostomes are also known as enterocoelomates, because their coelom develops through enterocoely.
Deuterostomia's sister clade is Protostomia, animals that develop mouth first and whose digestive tract development is more varied. Protostomia includes the ecdysozoans (panarthropods, nematoids, penis worms, mud dragons etc.) and spiralians (mollusks, annelids, flatworms, rotifers, arrow worms, etc.), as well as the extinct Kimberella.
Deuterostomia and Protostomia, together with their outgroup Xenacoelomorpha, constitute the large infrakingdom Bilateria, i.e. animals with bilateral symmetry and three germ layers.