Hemichordates and Invertebrate chordates 1 Animal innovations (Symplesiomorphies) Pharyngeal gill slits Dorsal hollow nerve cord Porifera Placozoa Cnidaria Ctenophora Platyhelminthes Gastrotricha Gnathostomulida Cycliophora Rotifera Annelida Mollusca Sipuncula Nemertea Bryozoa Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda Priapulida Kinorhyncha Loricifera Echinodermata Hemichordata Chordata Hemichordata (autapomorphies) Stomochord proboscis complex Glomerulus Porifera Placozoa Cnidaria Ctenophora Platyhelminthes Gastrotricha Gnathostomulida Cycliophora Rotifera Annelida Mollusca Sipuncula Nemertea Bryozoa Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda Priapulida Kinorhyncha Loricifera Echinodermata Hemichordata Chordata Page 1
Hemichordate Proboscis (protocoel) Collar (mesocoel) Branchiogenital trunk (metacoel) Anus Gill slits Intestinal trunk (metacoel) Hepatic trunk (metacoel) 4 Stomochord proboscis complex Mesocoel Heart vesicle Glomerulus Protocoel Mouth Stomocord 5 Acorn worm burrow 6 Page 2
Feeding Proboscis Rejected particles Gill pores Gut Collar Preoral ciliary organ Esophagus Food entering mouth 7 Locomotion 8 Chordates? 9 Page 3
Chordata (autapomorphies) Neurotube-notochord-mesoderm complex Pharyngeal slits and endostyle Post-anal tail and tadpole-like swimming Porifera Placozoa Cnidaria Ctenophora Platyhelminthes Gastrotricha Gnathostomulida Cycliophora Rotifera Annelida Mollusca Sipuncula Nemertea Bryozoa Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda Priapulida Kinorhyncha Loricifera Echinodermata Hemichordata Chordata Pikaia: The chordate ancestor 11 Neurotube-notochord-mesoderm complex Neural crest Endoderm Ectoderm 12 Page 4
Neurotube-notochord-mesoderm complex 13 Fibrous sheath Elastic sheath 14 Neurotube-notochord-mesoderm complex Nerve cord Myomere Kidney Dorsal aorta Mesentery 15 09:01 Page 5
Neurotube-notochord-mesoderm complex 16 Evolution of the nephros Glomerulus Archinephric duct Nephrostome Dorsal aorta Coelom Nephrostome Coelomic funnel 17 09:01 Nephron 18 09:01 Page 6
Origins of segmentation Ectoderm Nerve cord Somite (myomere) Archinephric duct Dorsal aorta Nephron Endoderm BIO3334 Invertebrate Zoology 19 Neurotube-notochord-mesoderm complex Somite Nephrostomes Archinephric duct 20 09:01 Pharyngeal gill slits Endostyle 21 Page 7
Segmentation Post anal segments (Tail) 22 Chordate Phylogeny Urochordata Vertebrata (Craniata) (autapomorphies) Assymetric planktonic larval stage Extension of muscular notochord beyond neural tube Staggered myomeres and mouth a modified gill slit BIO2135 Animal Form & Function 23 24 Page 8
Nerve cord Cecum Intestine Tail Mouth Endostyle Pharyngeal gill slits Atriopore Anus 25 Feeding Hatschek s pit Rostrum Buccal cavity Buccal cirri Wheel organ Mouth in velum Endostyle Gills 26 Circulatory system Dorsal aorta Anterior cardinal vein Posterior cardinal vein Dorsal aorta Branchial arteries Pharyngeal slits Ventral aorta Cecum Mesenteric arteries Intestine Subintestinal vein 27 Page 9
Cross section () Neural tube Myomeres Atrium Gill Bars Pharynx region Endostyle Intestinal region 28 Chordate Phylogeny Urochordata Vertebrata (Craniata) Symplesiomorphy Change in notochord from stack of coins to hollow elastic tube BIO2135 Animal Form & Function 29 Chordate Phylogeny Urochordata Vertebrata (Craniata) Urochordata (autapomorphies) Reduction of genome Tunicin cuticle Reversible heart beat BIO2135 Animal Form & Function 30 Page 10
Reversible heart beat Pharyngeal basket Cerebral ganglion Endostyle Gut Tunic Gonads Heart 31 Urochordates Atrial siphon Mouth Branchial siphon Atrium Endostyle Stigmata (Pharyngeal gill slits) Gonad Stomach Heart 32 Urochordate larva Incurrent siphon Excurrent siphon and anus Dorsal tubular nerve cord Endostyle Pharyngeal gill slits Post anal segments (Tail) 33 Page 11
Urochordate metamorphosis 34 Urochordate morphology Benthic (Sessile) Solitary Colonial Pelagic (Swimming) 35 Chordate Phylogeny Urochordata Vertebrata (Craniata) Vertebrata (autapomorphies) Neural crest cells Placodes, tripartite brain and cranium Axial skeleton with vertebrae BIO2135 Animal Form & Function 36 Page 12
Ammocoete (lamprey) larva 09:01 37 Ammocoete (lamprey) larva Nerve cord Digestive system Mouth Heart Gill pouches Anus 09:01 38 Page 13