Editing Hemichordate (section)

=== Neural system ===

A hollow [[neural tube]] exists among some species (at least in early life), probably a primitive trait that they share with the common ancestor of [[chordate|chordata]] and the rest of the deuterostomes.<ref>{{cite journal|last=Nomakstainsky|first=M|display-authors=etal|journal=Current Biology|date=11 August 2009|volume=19|pages=1264–9|doi=10.1016/j.cub.2009.05.063|pmid=19559615|title=Centralization of the deuterostome nervous system predates chordates|issue=15|doi-access=free|bibcode=2009CBio...19.1264N}}</ref> Hemichordates have a [[nerve net]] and longitudinal nerves, but no brain.<ref>{{cite journal | doi=10.1016/j.cub.2015.08.001 | title=Neural nets | year=2015 | last1=Hejnol | first1=Andreas | last2=Rentzsch | first2=Fabian | journal=Current Biology | volume=25 | issue=18 | pages=R782–R786 | pmid=26394095 | s2cid=18806753 | doi-access=free | bibcode=2015CBio...25.R782H }}</ref><ref>{{cite book | url=https://books.google.com/books?id=tu6XwCCRixsC&dq=%22weblike+nervous+system+that+runs%22&pg=PT138 | title=The Brain: Big Bangs, Behaviors, and Beliefs | isbn=9780300183566 | last1=Desalle | first1=Rob | last2=Tattersall | first2=Ian | date=30 April 2012 | publisher=Yale University Press }}</ref>

The nervous system of adult [[enteropneust]]s consists of:<ref>https://oxfordre.com/neuroscience/display/10.1093/acrefore/9780190264086.001.0001/acrefore-9780190264086-e-204</ref>
* the basiepidermal nerve net
* the [[dorsal nerve cord]]
* the [[ventral nerve cord]]
* the prebranchial nerve ring