Phylum Chordata Tunicates Amphioxus Phylum Chordata

Phylum Chordata Included are 48,000 species the majority of which are vertebrates 1,400 species are invertebrates All chordates share 4 characteristics at one point throughout the lifecycle Includes the tunicates, the lancelets (Amphioxus), and vertebrates Phylum Chordata

Taxonomic Summary Phylum Chordata Subphylum Urochordata Subphylum Cephalochordata Subphylum Vertebrata Phylum Chordata

Subphylum Urochordata Defining characteristics Notochord and nerve cord are found only in the larval stage Most of the urochordates are filter feeders Phylum Chordata

Colonial Species Phylum Chordata

Nice Tunic Soft exoskeleton made of cellulose with 2 external openings Some species have spicules and toxins in the tunicate Spicules Phylum Chordata

Filter Feeding

Sexual Reproduction Most colonial species retain eggs and fertilization is internal with development The larvae are microscopic, short-lived, non-feeding, pelagic tadpoles Phylum Chordata

Subphylum Cephalochordata Defining characteristics The notochord extends beyond the nerve cord to the anterior end of the animal The notochord is contractile, formed as a longitudinal series of flattened discs Phylum Chordata

A Little Ditty It’s a long way from amphioxus, It’s a long way to us To the meanest human cuss Goodbye to tails and gill slits, Hello: nails and hair! But we came from there Phillip H. Pope sing to the tune of “It’s a long way to Tipperary” Phylum Chordata

Anatomy Diagnostic chordate features are found in both the larvae and adult Resemble small fish with a poorly developed head Have cirri around a large mouth V-shaped body muscles (myomeres) extends the length of the body and are used for swimming and burrowing Phylum Chordata

Anatomy Phylum Chordata

Filter Feeders Filter feed using a special pharynx similar to tunicates Slotted pharynx supported by skeletal bars similar to acorn worms Phylum Chordata

Reproduction Separate sexes with gonads located in the atrial region Fertilization occurs in the water Developing young are free swimming propelled by cilia Phylum Chordata