bilaterian
Noun
Meaning
bilaterian (plural bilaterians or bilateria)
(zoology) Any animal that has bilateral symmetry, collectively grouped in the clade Bilateria.
Hyponyms
Examples
In most bilaterian embryos the blastopore, a dent in the outer wall, deepens to become the larva's gut, but in ectoprocts the blastopore disappears and a new dent becomes the point from which the gut grows.
The fundamental bilaterian body form is a tube with a hollow gut cavity running from mouth to anus, and a nerve cord with an enlargement (a "ganglion") for each body segment, with an especially large ganglion at the front, called the "brain".
Bottom: nervous system in isolation, viewed from above Worms are the simplest bilaterian animals, and reveal the basic structure of the bilaterian nervous system in the most straightforward way.
If chaetognaths branched off from the protostomes before they evolved their distinctive protostome embryonic characters, they may have retained deuterostome characters inherited from early bilaterian ancestors.