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Transcript 
Phylum Chordata
SBI 3U
What are Chordates?

Chordates are animals with a nerve cord, notochord
and gill slits (at least at some point in their lives)
Characteristics of Chordates
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Bilaterally symmetrical
Ventral heart
Body extends past anus into a tail
Nerve cord
Notochord
Gill slits
More about chordates
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Most recent group of animals
Make up only about 5% of animal species
What is a nerve cord?
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Unique to chordates
Dorsal nerve cord (dorsal=back side)
Found in the embryos of animals within the phylum
chordata
NOT the spinal cord  but it develops into one in
vertebrates
Part of the nervous system
Connects the brain with the lateral
muscles and other organs
What is a notochord?
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A notochord is a skeletal rod made up of cartilage
Found in all embryonic and some adult chordates
In vertebrates  only present during embryonic
development
Classification of Chordates
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Three subphyla: Cephalochordata, Urochordata and Vertebrata
Cephalochordata: such as lancelets
Urochordata: such as tunicates
Vertebrata: such as amphibians, reptiles, birds and mammals
Cephalochorata & Urochordata
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Filter-feeding marine organisms
Filter-feeding  pass water over a specialized filtering
structure
Have notochords
No backbones or vertebral columns
Transition from invertebrates  chordates
Example: Lancelet (cephalochordata)
Example: Tunicate
Vertebrata
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Approx. 95% of all chordates
Presence of vertebrae  hollow, cartilaginous, bony structure 
protects dorsal nerve cord
Endoskeleton
Large brain protected by skull
Advanced nervous system
Circulatory system
Large coelom  containing vital organs
Development of Appendages
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Two pairs of appendages  limbs
Improvement of locomotion
One of the defining features of vertebrates
Even snakes have them!
Skull
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Anterior skull with a large brain
Supports structures of the face and protects brain
Mouse
Human
Dog
Circulatory System
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Ventral heart  pumps blood throughout body  in the
process, delivering oxygen throughout
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