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Biology
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30-1 The Chordates
Photo Credit: ©Art Wolfe/Stone
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30-1 The Chordates Read Chapters 30 – 33 Test 3 will be based on Chapters 30 – 33,class notes, class handouts and the Fish and Rat Labs.
Photo Credit: ©Art Wolfe/Stone
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What Is a Chordate?
What Is a Chordate?
Members of the phylum Chordata are called chordates.
A chordate is an animal that has, for at least some stage of its life:
a dorsal, hollow nerve cord;
a notochord;
pharyngeal pouches;
a tail that extends beyond the anus.
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What Is a Chordate?
Characteristics of Chordates
Notochord
Muscle segments
Hollow nerve cord
All chordates share four characteristics: a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus. Some chordates possess all these characteristics as adults; others possess them only as embryos.
Tail
Anus
Mouth
Pharyngeal pouches
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What Is a Chordate?
The notochord is a long supporting rod that runs through the body just below the nerve cord.
Notochord
Most chordates have a notochord only when they are embryos.
In vertebrates, the backbone replaces the notochord.
How is an endoskeleton similar to an exoskeleton? How is it different? P768.
All chordates share four characteristics: a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus. Some chordates possess all these characteristics as adults; others possess them only as embryos.
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What Is a Chordate?
Pharyngeal pouches are paired structures in the throat (pharynx) region.
Pharyngeal pouches
All chordates share four characteristics: a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus. Some chordates possess all these characteristics as adults; others possess them only as embryos.
In fish – become the gills
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What Is a Chordate?
The tail can contain bone and muscle and is used for swimming by many aquatic species.
Tail
Tail that extend beyond the anus:
May only exist when the animal is an embryo
All chordates share four characteristics: a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus. Some chordates possess all these characteristics as adults; others possess them only as embryos.
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9. Most Chordates Are Vertebrates
What Is a Chordate?
Most Chordates Are Vertebrates
About 96 percent of all chordate species are vertebrates.
Most vertebrates have a vertebral column, or backbone.
In vertebrates, the dorsal, hollow nerve cord is called the spinal cord.
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11. Nonvertebrate chordates
What Is a Chordate?
Phylogeny of Chordates
Mammals
Birds
Reptiles
Amphibians
Bony fishes
Sharks
& their relatives
Jawless fishes
Nonvertebrate chordates
Although nonvertebrate chordates lack a vertebral column, they share a common ancestor with vertebrates.
Invertebrate ancestor
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12. Nonvertebrate Chordates
Tunicates (sea squirts)
Lancelets
Refer to notes from last class.
adult larvae
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30-1
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30-1
A characteristic of most, but not all, chordates is
pharyngeal pouches.
a backbone.
a hollow nerve cord.
a tail that extends beyond the anus.
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30-1
In vertebrates, the developing backbone replaces the
pharyngeal pouches.
hollow nerve cord.
notochord.
siphon and tunic.
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