1. Chordata

2. Phylum Chordata Bilateral, Deuterostomate development Notochord
Dorsal hollow nerve cord
Pharyngeal slits
Muscular Post-anal tail
Segmented musculature
Repeating units called somites

4. Chordate features Oldest group ( ancestral) Urochordata
The Tunicates, Sea Squirts
Chordate Features found in larval phase
Aid in dispersal, adults are sessile.
Today’s sessile tunicates are derived trait

5. Chordate Phylogeny

6. Subphylum Urochordata
Only larva has chordate characteristics
#63-x-section
#65

7. Tunicates

8. Tunicate larvae

9. Tunicates

11. atrial opening (water that passed through pharynx leaves this way)
nerve cord
notochord
gut
oral opening
atrial opening (water that passed through pharynx leaves this way)
pharynx with gill slits
Fig. 24.3, p. 385

12. Subphylum Cephalochordata
Come about by Paedogenesis (?)
Precocious sexual maturity in larvae
Adults now have all the chordate traits, and are motile
The lancelets have only a slight swelling , “anterior ganglia’ brain?

13. Subphylum Cephalochordata
# 66

14. Amphioxus

22. Chordate Phylogeny

23. Subphylum Craniata Cephalized Chordates Two sets of Hox genes
Brain, eyes, etc.
Skull
Two sets of Hox genes
Neural Crest –
Infolding of ectoderm
Cells spread through developing body
Form neurons and other features
Teeth, facial bones,
Pharanygeal slits paired with muscles & nerves that pump water through slits
More active metabolism

25. Class Mixini Jawless craniate Mixini – the hagfishes (not a fish)
Have cartilagnous, skull and notochord

26. Super Class - Vertebrata
More extensive skull
Backbone composed of vertebrae
Originally prongs of cartilage dorsally along nototchord protecting nerve chord
Later took over mechanical role of notochord
Later fins and other appendages form along vertebrae

27. Chordate Phylogeny

28. Class Cephalaspidomorphi
Lampreys
Have cartilaginous vertebrae-like extensions along notochord
Still jawless

29. Gnathostomes Vertebrates with true jaws Additional Hox gene cluster
Larger brains, better sense of smell sight
Lateral line system to sense water movement
Mineralized endoskeleton
Two sets of paired appendages.
these paired appendages first functioned in swimming.
In tetrapods, the appendages are modified as legs on land.

30. Class Chondrichthyes

31. What’s New in Bony Fish Bony Skeleton
Single Gill Opening – Operculum bellows water over gills
Swim bladder – gas from blood fills bladder, released to control buoyancy

32. Swim Bladder
Muscular
Valve
Gas Gland

34. Lobed-finned fish vs. Amphibian Bones

35. Class Amphibia

36. REPTILIA - Amniotes

37. MAMMALS

38. Monotremes Warm blooded Have hair Lay eggs
Young hatch and live outside mother
Make milk in glands, no nipples

39. Marsupials
Live birth to underdeveloped young. Placenta forms, but not a long a time.
Young crawl to pouch
Physically attach to nipple in pouch and feed off milk, finish development while nursing.
Stay with mother in pouch until able to survive outside

40. Eutherian mammals “Placental mammals”- live birth
Young held inside past egg feed development
feed trough an umbilical attachment to the placental
Born more developed than marsupials
Feed off milk from breast- Not physically attached to nipple