1. Invertebrate Chordates
Section 31.2

2. Chordate Characteristics
Endoskeleton is completely internal
Notochord develops along the back of the embryo
Notochord becomes the backbone in vertebrates
A hollow, dorsal nerve cord runs the length of the body
Pharyngeal pouches develop & become gills, glands, or the inner ear
A postanal tail that extends beyond the anus

3. Invertebrate Chordates
These are 2 small groups of chordates (have a notochord) that are invertebrates (without a backbone)
Urochordata – tunicates
Cephalochordata - lancelets

4. Tunicates
Only larvae have the chordate features (notochord, nerve cord, postanal tail) – adults lack them
Adults do keep the pharyngeal pouches
Sessile
Marine
Filter-feeding
All are hermaphrodites

5. Tunicates

6. Tunicates: also called ‘sea squirts’

7. Lancelets Fossils are much older than any fish species
Only a few centimeters long
V-shaped bundles of muscles arranged in segments
Live in shallow ocean water, with tails buried and heads exposed
Filter plankton out of the water
Sexes are separate

8. Lancelets have transparent skin