Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord...
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Transcript of Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord...
![Page 1: Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord 3.Pharyngeal slits.](https://reader036.fdocuments.in/reader036/viewer/2022062517/56649f385503460f94c54147/html5/thumbnails/1.jpg)
ChordatesCharacteristics that Unify this
Group: 1. Notochord 2. Hollow, dorsal nerve cord3. Pharyngeal slits
![Page 2: Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord 3.Pharyngeal slits.](https://reader036.fdocuments.in/reader036/viewer/2022062517/56649f385503460f94c54147/html5/thumbnails/2.jpg)
Chordate Characteristics
![Page 3: Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord 3.Pharyngeal slits.](https://reader036.fdocuments.in/reader036/viewer/2022062517/56649f385503460f94c54147/html5/thumbnails/3.jpg)
Notochords
• Long, flexible support rod
• Dorsal, just below nerve cord
• Usually replaced by backbone in early development
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Hollow, Dorsal Nerve Cord
• Just below the notochord
• Front end develops into the brain
• Many nerves branch to rest of body from this main cord
![Page 5: Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord 3.Pharyngeal slits.](https://reader036.fdocuments.in/reader036/viewer/2022062517/56649f385503460f94c54147/html5/thumbnails/5.jpg)
Comparison of Arthropods and Vertebrates
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Pharyngeal Slits
• In aquatic chordates, these develop into gill slits
• Only chordates have pharyngeal gill slits
![Page 7: Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord 3.Pharyngeal slits.](https://reader036.fdocuments.in/reader036/viewer/2022062517/56649f385503460f94c54147/html5/thumbnails/7.jpg)
Pharyngeal Slits
• In terrestrial chordates the pharyngeal slits close up at an early stage in development
• In humans, the embryo doesn’t ever develop actual slits, but does develop pharyngeal “pouches”
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![Page 9: Chordates Characteristics that Unify this Group: 1.Notochord 2.Hollow, dorsal nerve cord 3.Pharyngeal slits.](https://reader036.fdocuments.in/reader036/viewer/2022062517/56649f385503460f94c54147/html5/thumbnails/9.jpg)
Invertebrate Chordates – Tunicates and Lancelets
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Invertebrate Chordates – Tunicates
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Tunicates – Larvae and Adult
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Tunicates - larva• Tadpole-shaped
larvae are free swimming.
• Only the larvae have the notochord and dorsal nerve cord
• They Filter plankton and breathe through their pharyngeal gill slits
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Tunicates - adults
• Adults develop through metamorphosis of larval stage
• Are sessile, filter feed and breathe through the gill slits
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Lancelets• Fish-like shape• Half (at least) of
their body is buried in the sand
• Filter-feeders• Have mouth and
up to 100 pharyngeal slits along body
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Lancelets• Have
muscle/nerve arrangement similar to that found in ALL vertebrates
• No jaw• No
appendages
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