phylum chordata urochordata subphylum urochordata (tunicata
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Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
“Craniata” group
Subphylum Vertebrata
Superclass Agnatha
Superclass GnathostomataClass Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Urochordata
Sessile filter feeder – cilia move water and food, filtering in pharyngeal ‘pouch’ (pharynx)
Urochordata
Water + Food
In
Gets
filtered
Water
Out
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Endostyle – ciliated groove within pharynx
secretes mucous for food capture
metabolizes iodine - homologous to thyroid
Endostyle
UrochordataMonoecious (hermaphroditic) - each individual produces male and female gametes. Gametes
released
Urochordata
Tunic – polysacchrides w/tunicinsecreted by mantle
Adult lacks most chordate synapomorphies
Urochordata
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Urochordata larvae
Eyespot (ocellus) andstatocyst
Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
“Craniata” group
Subphylum Vertebrata
-Superclass Agnatha
Superclass GnathostomataClass Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Motile filterfeeders
Ciliated wheel organ and pharynx
Notochord – “hydroskeleton”
Stiffness of notochord under neural control
Cephalochordata
amphioxus
Notochord extends
into anterior end
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Amphioxus
Tail musculature and associated nerves & vessels are segmented.
‘Metamerism”
Cephalochordata
myomeres
Amphioxus
Circulatory system with dorsal and ventral aorta.
Cephalochordata
Metapleural fold – stability for swimming
Cephalochordata
In text, Euchordates = Somitichordates
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What were early chordates like?
Pikaia gracilens - 530 million years ago
myomeres (muscle blocks)
skeletal notochord
cephalization
Cambrian explosion - ~550 million y.a.
Burgess shale
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Phylum Chordata
Subphylum Urochordata (Tunicata)
Subphylum Cephalochordata
“Craniata” group
Subphylum Vertebrata
-Superclass Agnatha
-Superclass GnathostomataClass Placodermi
Class Chondrichthyes
Class Acanthodii
Class Osteichthyes
Class Amphibia
Class Reptilia
Class Mammalia
Class Aves
Contains hagfish and all vertebrata
Chordates with skulls, neural crest
Cranium is cartilagenous, fibrous or bony and encases brain and sense organs
Craniata
Hagfish
Lamprey
Sensory, digestive and respiratory anatomyCraniata
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Neural crest cellsNC cells are found in all craniates and give rise to a variety of structures
QuickTime™ and a Animation decompressor are needed to see this picture.
It’s nice to have a neural crest….pigment cells
gill arches, jaw
ganglia in ANS
base of skull
induce skin ‘structures’
cranial meninges
Selection for predatory characteristics
active feeders
muscular gut tube for filtering
Craniata vs. ‘protochordates’
Pikaia gracilens Haikouella
Conodonts - 540-230 m.y. ago
after Pikaia, the next fossil Chordates
microfossils of teeth, probably in pharynx
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A new hard substance appears: mineralized tissue – calcium phosphate (hydroxyapatite)
Cool thing about conodonts