Protostome

Protostomes; Temporal range: == Protostome Media == Proporus sp. -Acoela ; Portugal 20140812-DSC01434 (21371237591) ; Common carp (white background) ; Kimberella quadrata, a soft-bodied bilaterian animal from the Ediacaran biota of South Australia and Russia. Kimberella grew up to around 15 cm (6 in) long, though much smaller individuals have also been found, only a few millimeters in length. Kimberella has been found associated with scratch-mark ; Priapulus caudatus 20150625 ; PPycnophyes zelinkaei ; A horsehair worm (Phylum Nematomorpha), species Paragordius tricuspidatus ; Illustration by Carolyn Gast, National Museum of Natural History. From a condensed Smithsonian report, New Loricifera from Southeastern United States Coastal Waters. ; An Oroperipatus species found in Yasuni National Park, Ecuador ;
Scientific classification
Kingdom:	Animalia
Subkingdom:	Eumetazoa
Clade:	ParaHoxozoa
Clade:	Bilateria
Clade:	Nephrozoa
(unranked):	Protostomia; Grobben, 1908
Superphyla
	Ecdysozoa; Spiralia;

Protostomes are a nephrozoan taxon of animals above the level of phylum. It is not part of the normal system of classification.

They are a subtaxon of the Bilateria, and are contrasted with the deuterostomes. Protosomes are distingued by their embryo: in deuterostomes, the first opening (the blastopore) becomes the anus, while in protostomes it becomes the mouth.

DNA sequence analysis suggests that protostome animals can be divided into three major groups:

Ecdysozoa, e.g. arthropods, nematodes
Platyzoa, e.g. platyhelminthes, rotifers
Lophotrochozoa, e.g. molluscs, annelids

as well as a number of minor taxa, like the Chaetognatha.