Clade of animals whose mouth develops before the anus
Protostomes
Temporal range: Ediacaran - Recent
PreꞒ
Ꞓ
O
S
D
C
P
T
J
K
Pg
N
Scientific classification
Domain:
Eukaryota
Kingdom:
Animalia
Subkingdom:
Eumetazoa
Clade:
ParaHoxozoa
Clade:
Bilateria
Clade:
Nephrozoa
(unranked):
Protostomia Grobben, 1908
Superphyla
Ecdysozoa
Spiralia
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. This nature has since been discovered to be extremely variable among Protostomia's members, although the reverse is typically true of its sister clade, Deuterostomia.[1][2] Well known examples of protostomes are arthropods, molluscs, annelids, flatworms and nematodes. They are also called schizocoelomates since schizocoely typically occurs in them.
Together with the Deuterostomia and Xenacoelomorpha, these form the clade Bilateria, animals with bilateral symmetry, anteroposterior axis and three germ layers.[3]
^Hejnol, A.; Martindale, M. Q. (2009). "The mouth, the anus, and the blastopore - open questions about questionable openings". In M. J. Telford; D. T. J. Littlewood (eds.). Animal Evolution — Genomes, Fossils, and Trees. pp. 33–40.
^Martín-Durán, José M.; Passamaneck, Yale J.; Martindale, Mark Q.; Hejnol, Andreas (2016). "The developmental basis for the recurrent evolution of deuterostomy and protostomy". Nature Ecology & Evolution. 1 (1): 0005. doi:10.1038/s41559-016-0005. PMID 28812551. S2CID 90795.
^Hejnol, A.; Obst, M.; Stamatakis, A.; Ott, M.; Rouse, G. W.; Edgecombe, G. D.; et al. (2009). "Assessing the root of bilaterian animals with scalable phylogenomic methods". Proceedings of the Royal Society B: Biological Sciences. 276 (1677): 4261–4270. doi:10.1098/rspb.2009.0896. PMC 2817096. PMID 19759036.
typically true of its sister clade, Deuterostomia. Well known examples of protostomes are arthropods, molluscs, annelids, flatworms and nematodes. They are...
distinguishing characteristic, but deuterostomy has since been discovered among protostomes as well. This group is also known as enterocoelomates, because their...
basis for separating bilaterian animals into two natural groupings: the protostomes and deuterostomes. In animals at least as complex as an earthworm, a...
the mouth in protostomes, and the anus in deuterostomes. Many taxonomists now recognize at least two more superphyla among the protostomes, Ecdysozoa (molting...
to the type of body cavity they possess, such as pseudocoelomates and protostome coelomates. In amniotes and some invertebrates, the coelom is the large...
Lophotrochozoa (/ləˌfɒtroʊkoʊˈzoʊə/, "crest/wheel animals") is a clade of protostome animals within the Spiralia. The taxon was established as a monophyletic...
The Spiralia are a morphologically diverse clade of protostome animals, including within their number the molluscs, annelids, platyhelminths and other...
symmetric body plan. The vast majority belong to two large superphyla: the protostomes, which includes organisms such as the arthropods, molluscs, flatworms...
to this view, most researchers now regard phoronids as members of the protostome super-phylum Lophotrochozoa. Although analysts using molecular phylogeny...
always placed brachiopods as protostomes while another type has split between placing brachiopods among the protostomes or the deuterostomes. It was suggested...
understanding of the Cambrian explosion; if it was a mollusc, or at least a protostome, this would mean that the two dominant Nephrozoan lineages would have...
strictly related to and possibly belonging to Gnathifera, a clade of protostomes that do not belong to either Ecdysozoa or Lophotrochozoa. Chaetognaths...
555 million-year-old Kimberella was a member of the protostomes. If so, this means the protostome and deuterostome lineages must have split some time...
between protostomes and deuterostomes is based on the direction in which the mouth (stoma) develops in relation to the blastopore. Protostome derives...
Ecdysozoa (/ˌɛkdɪsoʊˈzoʊə/) is a group of protostome animals, including Arthropoda (insects, chelicerata (including arachnids), crustaceans, and myriapods)...
appears to have happened at least twice, following different paths in protostomes and deuterostomes. This accompanied or facilitated other important evolutionary...
in ontogeny is a criterion used to classify bilaterian animals into protostomes and deuterostomes. In the first multicellular animals, there was probably...
Mollusca is the second-largest phylum of invertebrate animals, after Arthropoda; members are known as molluscs or mollusks (/ˈmɒləsks/). Around 76,000 extant...
presence of a central nervous system. An alternative to the traditional protostome-deuterostome dichotomy, it has found weak support in several studies....
tube of an embryo forms as a blind pouch called the archenteron. In protostomes, the coelom forms by a process known as schizocoely. The archenteron...
can be found in species earlier than vertebrates; most recently in the protostome horseshoe crab species, putting the origins of the system back further...
lophophore. Molecular phylogenetic analyses suggest that lophophorates are protostomes, but on morphological grounds they have been assessed as deuterostomes...
glutamate at the glutamate-gated chloride channel that is specific to protostome invertebrates, with minor effects on gamma-aminobutyric acid receptors...
Eumetazoa, divided into four superphyla, Deuterostomia, and the three Protostome superphyla, Ecdysozoa, and the two Spiralia superphyla, Platyzoa and Lophotrochozoa...
Look up seta in Wiktionary, the free dictionary. In biology, setae /ˈsiːtiː/ (sg.: seta /ˈsiːtə/; from the Latin word for "bristle") are any of a number...
Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode...
Tactopoda or Arthropodoidea is a proposed clade of protostome animals that includes the phyla Tardigrada and Euarthropoda, supported by various morphological...
Nematomorpha (sometimes called Gordiacea, and commonly known as horsehair worms, hairsnakes, or Gordian worms) are a phylum of parasitoid animals superficially...
Annelids are considered members of the Lophotrochozoa, a "super-phylum" of protostomes that also includes molluscs, brachiopods, and nemerteans. The basic annelid...
Global Information
