presentation

1. Phylum
Chordata
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2. Phylum Chordata
● Diverse phylum, but much less than
arthropods, or molluscs
● Most advanced of the animal
phylum
● Most complex anatomy (e.g.,
nervous, circulatory systems etc.)
● Some of the largest animals that
have ever lived
2

3. Phylum Chordata
Membership based on possession of five characteristics
- Do not have to be present throughout entire lifetime
- Only during some life stage
1. Notochord
2. Pharyngeal gill slits (pouches)
3. Endostyle or thyroid gland
4. Post-anal tail
5. Dorsal tubular nerve cord
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4. Phylum Chordata
1. Notochord
- Flexible rod-like structure
- Enclosed by a fibrous sheath
- Extends the length of the body
- Provides basic support
- Serves as main axis of support and for muscle
attachment for undulatory, fish-like movements
- First part of skeleton in embryo
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5. Phylum Chordata
Notochord
- In primitive chordates, the notochord
persists throughout life
- Most chordates replaces it with the
vertebral bone
- Remnants remain as intervertebral discs
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6. Phylum Chordata
2. Pharyngeal (gill) slits
- Slit -like openings leading from throat to
outside
- First evolved as filter feeding apparatus
- Still used as such in some groups
- Used as gills in many aquatic forms
- Many groups only have as embryos and
loose as adults
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7. Phylum Chordata
Pharyngeal (gill) slits
- Slit -like openings leading from throat to
outside
- First evolved as filter feeding apparatus
- Still used as such in some groups
- Used as gills in many aquatic forms
- Many groups only have as embryos and
loose as adults
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8. Phylum Chordata
3. Endostyle or thyroid gland
- Tissue only found in chordates
- Originally part of the feeding apparatus
- Secreted mucus to trap food inside the
pharyngeal cavity
- In most chordates becomes an endocrine
gland
- Helps control metabolism
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9. Phylum Chordata
Endostyle or thyroid gland
- Tissue only found in chordates
- Originally part of the feeding apparatus
- Secreted mucus to trap food inside the
pharyngeal cavity
- In most chordates becomes an endocrine
gland
- Helps control metabolism
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10. Phylum Chordata
4. Post-anal tail
- Mobility for aquatic chordates
- Efficient propulsion unit
- Fins added for increased efficiency
- Terrestrial chordates use tail for
leverage and balance
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11. Phylum Chordata
Post-anal tail
- Mobility for aquatic chordates
- Efficient propulsion unit
- Fins added for increased efficiency
- Terrestrial chordates use tail for
leverage and balance
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12. Phylum Chordata
5. Dorsal tubular nerve cord
- Most inverts have the nerve cord
as ventral
- Paired with paired ganglia along its
length
- Chordates have single hollow
nerve cord
- Anterior enlarged into brain
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13. Phylum Chordata
Three major Subphyla
- Urochordata (tunicates) - tail
chordates
- Cephalochordata (lancelets) - head
chordates
- Vertebrata (vertebrates)
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14. 14

15. Subphylum Urochordata
Tunicates and sea squirts
- 1,600 species
- All marine
- All depths
- Adult form as suspension feeder
(catch particles in water)
- Many live colonially on rocks or
other hard surfaces
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16. Subphylum Urochordata
Tunicates and sea squirts
- Adults lack all chordate characters
- More sponge-like
- Sessile
- Lack a coelom
- Pump water through siphons
- Tadpole larvae have all typical
chordate features
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17. Subphylum Urochordata
Tunicates and sea squirts
- Adults have tough, nonliving
covering
- Tunic
- Filter feeders
- Incurrent siphon → pharyngeal slits →
atrium → excurrent siphon
- Endostyle secretes mucus on pharynx
- Mucus and cilia move food to
mouth
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18. Subphylum Urochordata
Tunicates and sea squirts
- Respiration
- Pharynx serves all functions
- Circulation
- Open circulatory system
- Small heart with two major vessels
- Excretion
- No specialized organs
- Reproduction
- All monoecious
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19. Subphylum Cephalochordata
Lancelets
- 29 species
- Closest living relatives to
vertebrates
- Several characters intermediate
between vertebrates and
invertebrates
- All chordate characters as adults
- Lack internal skeleton
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20. Subphylum Cephalochordata
Lancelets
- Burrowers and swimmers
- Body laterally compressed and fish- or
eel-like
- Ventral surface is flattened and
bears metapleural folds
- Most of time spent burrowed with
only head exposed
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21. Subphylum Cephalochordata
Lancelets
- Fish-like fins with reinforcing rays
- Movements
- V-shaped bundles of muscles
(myotomes)
- Feeding and digestion
- Filter feeders
- Mouth surrounded by oral hood, wheel
organ, and cilia
- All work to draw in water
- Pharynx strains particles from
water
- Hepatic caecum (liver) 21

22. Subphylum Cephalochordata
Lancelets
- Circulation
- Closed system but no heart
- Respiration
- Some through pharynx
- Most via diffusion across body wall
- Nervous system
- Hollow nerve cord
- Photoreceptive cells
- Excretion
- Nephridia similar to annelids
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23. Subphylum Cephalochordata
Lancelets
- Reproduction
- All diecious
- Larvae resemble adults
- But covered in cilia
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24. Subphylum Vertebrata
Most complex group of animals
Fish became first true vertebrates
- Oldest known fossils of a vertebrate (560
mya)
Only one invertebrate group evolved flight
- Two (3*) vertebrates evolved powered flight
- All other show some gliding
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25. Subphylum Vertebrata
Most complex group of animals
Major characters
1. Internal jointed skeleton
- Bone or cartilage
- Living tissue
- Cartilage first, then bone
- Axial and appendicular skeleton
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26. Subphylum Vertebrata
Most complex group of animals
Major characters
2. Segmented skeletal muscles
- W-shaped muscle fibers
- Heightened control of
body movements
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27. Subphylum Vertebrata
Most complex group of animals
Major characters
3. Complex skin
- Multilayered
- Dermis and epidermis
- Contains
- Sensory receptors, glands,
keratin structures (hair,
scales, feathers)
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28. Subphylum Vertebrata
Most complex group of animals
Major characters
4. More efficient digestive system
- Food moved by peristaltic
contractions not cilia
- Acid producing stomach
- Accessory glands
- Pancreas, liver
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29. Subphylum Vertebrata
Most complex group of animals
Major characters
5. Efficient respiratory system tied to
circulation
- Pharyngeal slits for filtering
became functional gills
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30. Subphylum Vertebrata
Most complex group of animals
Major characters
6. Increasingly efficient circulation
- Ventral heart
- Closed circuit
- heart chambers (2, 3, 4)
- RBC’s use hemoglobin as
respiratory pigment
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31. Subphylum Vertebrata
Most complex group of animals
Major characters
7. Most complex nervous
system
- Well developed head
and sensory organs
- Lifestyle shift from
filter feeding to
predation
- CNS and PNS
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32. Subphylum Vertebrata
Most complex group of animals
Major characters
8. Improved efficiency of
excretory organs
- Paired kidneys
- Dual role for metabolic
wastes and
osmoregulation
9. Almost all are dioecious and
reproduce sexually 32

33. Classification of vertebrates
- Jaws present or absent
- Agnatha - jawless
- Gnathostomata - mouth with jaws
- Fins versus walking legs
- Pisces - paired fins for swimming
- Tetrapoda - paired limbs for terrestrial locomotion
- Development
- Anamniotes - offspring do not develop in a fluid-filled sac; fishes and amphibians
- Amniotes - offspring do develop in a fluid-filled sac; reptiles, birds, mammals
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