Phylum Chordata A.K.A. Chordates

Chordate Cladogram

Four Distinguishing Features Single, hollow, dorsal nerve cord Gill or pharyngeal slits (or pouches)--small openings along anterior part of body or pharynx Notochord: flexible rod for support that lies between the nerve cord and gut Post-anal tail: tail that extends beyond the anus

Nerve Cord Runs along the dorsal or back side of a chordate Connects nerves to internal organs, muscles and sense organs

Notochord A long supporting rod located just below the nerve cord (ventral to the nerve cord) All chordates begin life with the notochord, but do not always retain it when they reach adulthood (like the human post-anal tail) Notochord is usually replaced with backbone in most vertebrates

Pharyngeal Pouch Series of paired structures that develop into gills in some vertebrates like lancelets and tunicates (and fish too) In humans they develop into the internal ear organs and some throat organs like the parathyroid

Chordate characteristics http://www.biog1105-1106.org/labs/deuts/chordates.html

Subphylum Urochordata A.K.A. tunicates SEA SQUIRTS 3,000 species; all marine Invertebrates Sessile Filter feeders Larval form has all four characteristics of chordates; adults do not

Subphylum Urochordata A.K.A. tunicates SALPS Planktonic Filter feeders Warm water Invertebrates http://www.flickr.com/photos/31124758@N00/165884673/

Subphylum Cephalochordata A.K.A. Lancelets (amphioxis) 23 species 7 cm long, similar in shape to a fish Retains chordate characteristics entire life Invertebrate (lack a backbone) Filter feeders using its pharynx with pharyngeal slits; inhabit soft bottoms

Subphylum Vertebrata A.K.A. Vertebrates Have a backbone; usually made of bony segments called vertebrae Bilateral symmetry Endoskeleton Complete digestive system Closed circulatory system 96% of all chordates are in this phylum Include: fish, reptiles, birds and mammals