Chordate Evolution

Flashcards covering key vocabulary and concepts from the Chordate Evolution lecture.

Notochord

Flexible, rod-like structure that extends the length of the body in chordates.

Pharyngeal slits

Connects the pharynx with the external environment in chordates; used for filter feeding or as gills.

Post-anal tail

Extends beyond the anus in chordates.

Dorsal hollow nerve cord

Runs along the length of the body and innervates muscles attached to the notochord; forms from infolding of ectoderm.

Non-Vertebrate Chordates

Chordates that have notochords but do not form vertebrae or other bones.

Urochordata

Examples include Ascidiacea (sea squirts), Thaliacea (salps), and Appendicularia (larvaceans).

Cephalochordata

Lancelets; chordates with no brain, use Hox genes to form a cranial bulb.

Vertebrate Chordates

Chordates with a vertebral column and a distinct head.

Pyrosomes

Colonial, with multiple tiny ascidian-like zooids arranged in a cylinder, a form of Thaliacea.

Vertebral column

Replaces the notochord during embryonic development in vertebrates; encloses and protects the nerve cord.

Hindbrain

Extension of spinal cord, primarily coordinates motor reflexes.

Midbrain

Deals with visual information in vertebrates.

Forebrain

Deals with olfactory information in vertebrates.