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Introduction to Deuterostomes. Quick Look at Hemichordata. Deuterstome Definition. eucoelomate, bilateral eumetazoans how embryonic mouth is formed 2 nd opening of gut to ectoderm blastopore becomes anus. sea urchin embryo: Campbell Fig. 47.9. Animal Phylogeny (review). Deuterostomia.
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Introduction to Deuterostomes Quick Look at Hemichordata
Deuterstome Definition • eucoelomate, bilateral eumetazoans • how embryonic mouth is formed • 2nd opening of gut to ectoderm • blastopore becomes anus sea urchin embryo: Campbell Fig. 47.9
Animal Phylogeny(review) Deuterostomia Parazoa (Porifera) Radiata (Cnidaria) Ecdysozoa Spiralia Protostomia Bilateria Eumetazoa Animalia
Deuterostome Phylogeny Vertebrata Urochordata Cephalochordata Craniata Phylum Echinodermata Hemichordata Chordata Deuterostomia
Characteristics of Hemichordates • Proboscis, collar, trunk body regions. • Tricoelomic, like echinoderms and ectoprocts • Deuterostomes, like echinoderms and chordates • They have no notochord • Filtering slits in pharynx, like Chordata (feeding and respritory function). • But anus is terminal (no tail) • No myomeres • Main nerve cord has both dorsal and ventral branches
Hemichordate larvae • Planktonic • Ciliated, complete gut • Not a trochphore larvae • Resembles a starfish larvae