Ambulacraria

Ambulacrarians Temporal range: Late Ediacaran - Recent
Various sea stars and sea urchins among mussel shells in the rocky intertidal zone of Kachemak Bay.
Scientific classification
Kingdom:	Animalia
Subkingdom:	Eumetazoa
(unranked):	Bilateria
Superphylum:	Ambulacraria
Phyla
Echinodermata (20,000 species) Hemichordata (71 species)

Ambulacraria or Coelomopora is a clade of invertebrate phyla which includes echinoderms and hemichordates; a member of this group is called an ambulacrarian. The Ambulacraria are part of the Deuterostomes, a larger clade that also includes the Chordata and Vetulicolia.

The two living phyla with representative organisms are:

• Phylum Echinodermata (sea stars, sea urchins, brittle stars, sea cucumbers, feather stars, sea lilies, etc.)
• Phylum Hemichordata (acorn worms, Pterobranchia, and possibly graptolites)

The phylum Xenoturbellida (two species of worm-like animals) has previously been considered to be in this clade, but is now considered to be placed more basally among Metazoans.^[1]

Fossil taxa that may lie on the stem lineage:

• ?Superphylum Ambulacraria#
  • unranked clade Cambroernida
    • unranked clade = Eldoniida
    • † Herpetogaster Caron, Conway Morris & Shu, 2010^[2] - with one species: † Herpetogaster collinsi Caron, Conway Morris & Shu, 2010^[2]

References

1. Edgecombe, Gregory D.; Giribet, Gonzalo; Dunn, Casey W.; Hejnol, Andreas; Kristensen, Reinhardt M.; Neves, Ricardo C.; Rouse, Greg W.; Worsaae, Katrine; Sørensen, Martin V. (2011). "Higher-level metazoan relationships: recent progress and remaining questions.". Organisms, Diversirt and evolution. doi:10.1007/s13127-011-0044-4.
2. Caron, J.; Conway Morris, S.; Shu, D.; Soares, D. (2010). Soares, Daphne, ed. "Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes". PLoS ONE 5 (3): e9586. doi:10.1371/journal.pone.0009586. PMC 2833208. PMID 20221405.