CHORDATA
GENERAL CHARACTERISTICS
- possesses the following (for at least some period of their life cycle):
- notochord - a cartilaginous rod running underneath and supporting the nerve
cord
- dorsal nerve cord - a bundle of nerve fibers which runs down the "back" and
connects the brain with the lateral muscles and other organs
- pharyngeal slits - a series of openings that connect the inside of the throat to
the outside of the "neck", often but not always used as gills
- post-anal tail - an extension of the body past the anal opening
DISTINCT CHARACTERISTICS
, A. TRADITIONAL (based on morphological characteristics)
B. CALCICHORDATE (based on Jefferies’ Calcichordate Hypothesis)
C. MOLECULAR (DNA evidence; currently most accepted)
HEMICHORDATES CHORDATES
Pharynx with multiple gill slits
Dorsal nerve cord
SIMILARITIES Ventral blood vessel
Bilateral symmetry
Gill slits
Notochord
Stomochord (precursor Post-anal tail
DIFFERENCES to notochord) In
Mesocoelomic cord vertebrates:
Bony
PHYLUM CHORDATA
Vetulicolians
Calcichordates
Urochordates
Cephalochordates
Conodonts
GENERAL CHARACTERISTICS
- possesses the following (for at least some period of their life cycle):
- notochord - a cartilaginous rod running underneath and supporting the nerve
cord
- dorsal nerve cord - a bundle of nerve fibers which runs down the "back" and
connects the brain with the lateral muscles and other organs
- pharyngeal slits - a series of openings that connect the inside of the throat to
the outside of the "neck", often but not always used as gills
- post-anal tail - an extension of the body past the anal opening
DISTINCT CHARACTERISTICS
, A. TRADITIONAL (based on morphological characteristics)
B. CALCICHORDATE (based on Jefferies’ Calcichordate Hypothesis)
C. MOLECULAR (DNA evidence; currently most accepted)
HEMICHORDATES CHORDATES
Pharynx with multiple gill slits
Dorsal nerve cord
SIMILARITIES Ventral blood vessel
Bilateral symmetry
Gill slits
Notochord
Stomochord (precursor Post-anal tail
DIFFERENCES to notochord) In
Mesocoelomic cord vertebrates:
Bony
PHYLUM CHORDATA
Vetulicolians
Calcichordates
Urochordates
Cephalochordates
Conodonts
