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Any of a numerous animals of the group Deuterostomia, in which the anus develops from the first opening in the embryo and the mouth develops later, and including the echinoderms, hemichordates, and chordates.

[From New Latin Deuterostomia, taxon name : deutero- + New Latin stoma; see stoma.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


any member of the major group of animals defined by the fact that during early embryonic development the first opening to form becomes the anus of the animal. The opposite is protostome
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈdu tər əˌstoʊm, ˈdyu-)

1. a mouth that develops separately from the blastopore.
2. an animal with this form of development, as an echinoderm or chordate.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
References in periodicals archive ?
Deuterostome neuroanatomy and the body plan paradox.
"We think that as an early deuterostome this may represent the primitive beginnings of a very diverse range of species, including ourselves," study co-author Simon Conway Morris from the University of Cambridge, said in a ( statement .
They are wide-spread, occur both in pro- and eukaryotes, in particular in bacteria and are found in some viruses, protozoa, a few insect species and regularly in deuterostome animals, from echinoderms onward.
Another very primitive stem group of deuterostomes, called ventulicolians, has also recently been described that might represent the anatomy of organisms near the base of the deuterostome evolutionary branch that were ancestral to both the chordates and echinoderms.
Of course, eyes are characteristic of the vertebrates in the deuterostome group.
We recently reported that larval sea stars are capable of complete regeneration of missing body parts, providing a new deuterostome model for the study of regeneration.
Despite being trained in comparative anatomy, or perhaps because of it, I was distrustful of some of the morphological criteria - for example, diploblastic versus triploblastic, or proterostome versus deuterostome - used in reconstructing phylogeny.
Analyses of their mitochondrial genome suggest a deuterostome affinity of the clade (Philippe et al., 2011; Robertson et al., 2017), but large-scale phylogenomic studies suggest that it is a sister group to all other extant bilaterians (Nephrozoa) (Hejnol et al., 2009; Cannon et al., 2016).
Within the deuterostome clade, however, few animals are capable of complete nervous system regeneration after total neural ablation.