Hemichordates and Invert chordates
Hemichordates and
Invertebrate chordates
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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
Animal innovations
(Symplesiomorphies)
• Pharyngeal gill slits
• Dorsal hollow nerve cord
!
!
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
BIO 2135 Animal Form and Function
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Hemichordates and Invert chordates
Hemichordate
Collar
(mesocoel)
Proboscis
Branchiogenital
trunk (metacoel)
(protocoel)
Gill slits
Anus
Hepatic trunk
Intestinal trunk (metacoel)
(metacoel)
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Stomochord proboscis
complex
Mesocoel
Heart vesicle
Glomerulus
Protocoel
Mouth
BIO2135 Animal Form and Function
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Stomocord
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Acorn worm burrow
BIO2135 Animal Form and Function
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BIO 2135 Animal Form and Function
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Hemichordates and Invert chordates
Feeding
Rejected particles
Gill pores
Proboscis
Gut
Collar
Preoral ciliary organ
Esophagus
Food entering mouth
BIO2135 Animal Form and Function
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Locomotion
BIO2135 Animal Form and Function
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Chordates?
BIO2135 Animal Form and Function
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BIO 2135 Animal Form and Function
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Hemichordates and Invert chordates
!
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
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Neurotube-notochord-mesoderm complex
Notochord
Neural crest
Endoderm
Ectoderm
BIO2135 Animal Form and Function
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BIO 2135 Animal Form and Function
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Hemichordates and Invert chordates
Neurotube-notochord-mesoderm complex
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Notochord
Elastic sheath
Fibrous sheath
Notochord
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Neurotube-notochord-mesoderm complex
Nerve cord
Myomere
Notochord
Kidney
Dorsal aorta
BIO2135 Animal Form and Function
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Mesentery
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Hemichordates and Invert chordates
Neurotube-notochord-mesoderm
complex
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Evolution of the nephros
Archinephric duct
Glomerulus
Nephrostome
Dorsal aorta
Coelom
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Nephrostome
Coelomic funnel
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Nephron
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Hemichordates and Invert chordates
Origins of segmentation
Ectoderm
Somite (myomere)
Nerve cord
Archinephric duct
Notochord
Dorsal aorta
Nephron
Endoderm
BIO3334 Invertebrate Zoology
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Neurotube-notochord-mesoderm complex
Somite
Nephrostomes
Archinephric duct
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Pharyngeal gill slits
Endostyle
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Hemichordates and Invert chordates
Segmentation
Post anal segments (Tail)
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Chordate Phylogeny
Cephalochordata
Urochordata
Vertebrata
(Craniata)
!
! Cephalochordata
(autapomorphies)
• Assymetric planktonic larval stage
• Extension of muscular notochord
beyond neural tube
• Staggered myomeres and mouth a
modified gill slit
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Cephalochordata
BIO2135 Animal Form and Function
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Hemichordates and Invert chordates
Cephalochordata
Nerve cord
Notochord
Cecum Intestine
Mouth
Endostyle
Pharyngeal
gill slits
Tail
Atriopore
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Feeding
Anus
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Notochord
Hatschek’s pit
Rostrum
Buccal
cavity
Buccal cirri
Wheel organ
Mouth in velum Endostyle
BIO2135 Animal Form and Function
Gills
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Circulatory system
Dorsal aorta
Anterior
cardinal
vein
Posterior
cardinal
vein
Dorsal aorta
Mesenteric
arteries
Branchial
arteries
Intestine
Pharyngeal
slits
Subintestinal vein
Ventral aorta
Cecum
BIO2135 Animal Form and Function
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Hemichordates and Invert chordates
Cross section
(Cephalochordata)
Neural tube
Notochord
Myomeres
Atrium
Gill Bars
Endostyle
Pharynx region
Intestinal region
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Université d’Ottawa / University of Ottawa
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Chordate Phylogeny
Cephalochordata
Urochordata
Vertebrata
(Craniata)
!
! Symplesiomorphy
• Change in notochord from “stack of
coins” to hollow elastic tube
BIO2135 Animal Form & Function
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Université d’Ottawa / University of Ottawa
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Chordate Phylogeny
Cephalochordata
Urochordata
Vertebrata
(Craniata)
!
! Urochordata
(autapomorphies)
• Reduction of genome
• Tunicin cuticle
• Reversible heart beat
BIO2135 Animal Form & Function
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BIO 2135 Animal Form and Function
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Hemichordates and Invert chordates
Reversible heart beat
Pharyngeal
basket
Cerebral
ganglion
Endostyle
Gut
Tunic
Gonads
Heart
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Urochordates
Atrial siphon
Mouth
Branchial
siphon
Atrium
Endostyle
Stigmata (Pharyngeal gill slits)
Gonad
Stomach
Heart
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Urochordate larva
Incurrent
siphon
Excurrent siphon
and anus
Endostyle
Pharyngeal gill slits
Dorsal tubular
nerve cord
Notochord
Post anal segments (Tail)
BIO2135 Animal Form and Function
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BIO 2135 Animal Form and Function
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Hemichordates and Invert chordates
Urochordate metamorphosis
BIO2135 Animal Form and Function
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Urochordate morphology
● Benthic (Sessile)
– Solitary
– Colonial
● Pelagic (Swimming)
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Université d’Ottawa / University of Ottawa
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Chordate Phylogeny
Cephalochordata
Vertebrata
Urochordata
(Craniata)
!
! Vertebrata
(autapomorphies)
• Neural crest cells
• Placodes, tripartite brain and cranium
• Axial skeleton with vertebrae
BIO2135 Animal Form & Function
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Hemichordates and Invert chordates
Cephalochordata
Ammocoete (lamprey) larva
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Ammocoete (lamprey)
larva
Nerve cord
Mouth
Notochord
Heart
Gill pouches
BIO2135 Animal Form and Function
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Digestive system
Anus
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