The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as jellyfish and starfish have a decentralized nervous system without a brain, while sponges lack any nervous system at all. In vertebrates, the brain is located in the head, protected by the skull and close to the primary sensory apparatus of vision, hearing, balance, taste, and smell[WP].
Comment:
[homology-note] "(...) at some stage of its development, every chordate exhibits five uniquely derived characters or synapomorphies of the group: (...) (4) a single, tubular nerve cord that is located dorsal to the notochord (...) (reference 1); The neural tube is destined to differentiate into the brain and spinal cord (the central nervous system) (reference 2).[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0000157", ontology="VHOG", source="ISBN:978-0030223693 Liem KF, Bemis WE, Walker WF, Grande L, Functional Anatomy of the Vertebrates: An Evolutionary Perspective (2001) p.28, ISBN:978-0072528305 Kardong KV, Vertebrates: Comparative Anatomy, Function, Evolution (2006) p.165", source="http://bgee.unil.ch/"}
Synonyms:
related_synonym:
encephalon; suprasegmental levels of nervous system; suprasegmental structures; synganglion; the brain