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Phylum Chordata. Phylum Chordata. Deuterostomes The four traits ALWAYS Notochord Pharyngeal slits/pouches Hollow, dorsal nerve cord Postanal tail Other traits Endostyle or thyroid gland Segmental musculature. It’s What All the Chordates are Wearing.
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Phylum Chordata • Deuterostomes • The four traits ALWAYS • Notochord • Pharyngeal slits/pouches • Hollow, dorsal nerve cord • Postanal tail • Other traits • Endostyle or thyroid gland • Segmental musculature
Stages & Events of Chordate Embryogenesis Developmental Process Embryonic Stage Zygote Morula Blastula Gastrula Neurulation Neurula Pharyngula Fetus
Notochord • Embryonic mesodermal structure • Induces neural tube formation • Serves as a dorsal support structure
Notochord & Formation of Neural Tube NT N NT N
Chordate Cladistics
Phylogenetic Relationship between Echinoderms, Hemichordates & Chordates
Phylum Chordata, Subphylum Urochordata • Protochordates • SP Urochordata • Notochord only in tail • Tadpole-like larvae • Class Ascidiacea • Class Thaliacea • Class Larvacea Larvacian Ascidian Thaliacian
Solitary Ascidians Clavelina puertosecensis
Phylum Chordata Subphylum Cephalochordata • Maintain chordate structures throughout life • Segmental myomeres very apparent • Notochord extends entire length of body
Amphioxus Maintains All Chordate Characters • Notochord • Dorsal neural tube • Pharyngeal slits/pouches originate from neural crest • Analogous to gill slits, inner ear & larynx • Postanal tail • Extension of body muscle beyond anal opening tail
Pikaia • Earliest known fossil chordate • Burgess shale of BC • Obvious similarity to cephalochordates