Deuterostomia
| Deuterostomes Temporal range: Cambrian - Present 521–0 Ma |
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|---|---|
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| A sea cucumber | |
| Scientific classification | |
| Kingdom: | Animalia |
| Clade: | Nephrozoa |
| Superphylum: |
Deuterostomia Grobben, 1908 |
| Phyla | |
Deuterostomes (taxonomic term: Deuterostomia; from the Greek: "mouth second") are any members of a superphylum of animals. It is a sister clade of Protostomia, with which it forms the Nephrozoa clade.
Deuterostomia is a subtaxon of the Bilateria branch of the subkingdom Eumetazoa, within Animalia, and are distinguished from protostomes by their deuterostomic embryonic development; in deuterostomes, the first opening (the blastopore) becomes the anus, while in protostomes, it becomes the mouth. (It is worth noting that there are some occurrences of Deuterostomy among Protostomes.)
Deuterostomes are also known as enterocoelomates because their coelom develops through enterocoely.
There are three major clades of deuterostomes:
Previously, Deuterostomia also included the phyla Brachiopoda, Bryozoa, Chaetognatha, and Phoronida based on embryological characteristics.
However, Superphylum Deuterostomia was redefined in 1995 based on DNA molecular sequence analyses when the lophophorates were removed from it and combined with other protostome animals to form superphylum Lophotrochozoa. The phylum Chaetognatha (arrow worms) may belong here, but molecular studies have placed them in the protostomes more often.
Extinct deuterostome groups may include the phylum Vetulicolia, other extinct lineages may be found in future.
Echinodermata and Hemichordata form the clade Ambulacraria.
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