1. Chordates Characteristics that Unify this Group: Notochord
Hollow, dorsal nerve cord
Pharyngeal slits

2. Chordate Characteristics

3. Notochords Long, flexible support rod Dorsal, just below nerve cord
Usually replaced by backbone in early development

4. 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

5. Comparison of Arthropods and Vertebrates

6. Pharyngeal Slits In aquatic chordates, these develop into gill slits
Only chordates have pharyngeal gill slits

7. 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”

9. Invertebrate Chordates – Tunicates and Lancelets

10. Invertebrate Chordates – Tunicates

11. Tunicates – Larvae and Adult

12. 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

13. Tunicates - adults
Adults develop through metamorphosis of larval stage
Are sessile, filter feed and breathe through the gill slits

15. 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

16. Lancelets
Have muscle/nerve arrangement similar to that found in ALL vertebrates
No jaw
No appendages