Chordata

Question 1

5 hallmarks of chordates

Answer 1

1. Notochord
2. Dorsal hollow nerve cord
3. Pharyngeal pounches or slits
4. Endostyle for filter feeding
5. Postanal tail for propulsion

Question 2

5 hallmarks of chordates

1.Notochord

Answer 2

Flexible, rod-like body of fluid-filled cells enclosed by a fibrous sheath
* Persists throughout life in jawless vertebrates and protochordates
* Becomes the vertebral column in all jawed vertebrates

Question 3

5 hallmarks of chordates

2.Dorsal hollow nerve cord

Answer 3

• Hollow (solid in invertebrates)
• Dorsal to digestive tract & notochord (ventral in invertebrates)
• Anterior end forms the brain & the rest is the spinal cord

Question 4

5 hallmarks of chordates

3.Pharyngeal Pouches or Slits

Answer 4

Openings that lead from the pharyngeal cavity to the outside
* Protochordates: functions as a filter-feeding apparatus
* Aquatic chordates: bear gills used in gas exchange
* Tetrapods: Only present in the embryonic stage

Question 5

5 hallmarks of chordates

4.Endostyle/Thyroid

Answer 5

Endostyle
* Secretes mucus that traps food particles brought into the pharyngeal cavity
* Present in protochordates and lamprey larvae

Thyroid
* regulates metabolism & helps to produce/regulate other hormones
* Present in adult lamprey and remainder of vertebrates

Question 6

5 hallmarks of chordates

5.Postanal tail

Answer 6

• Provides motility in protochordates
• Increased in fishes
• Vestige in humans

Question 7

Protochordata

Not monophyletic

Answer 7

Urochordata & Cephalochordata
* Invertebrate chordates
* Include hallmarks of chordates but no cranium/vertebrae

Question 8

Protochordata

Urochordata

Answer 8

• Tunicates
• Only the larval form bears all the chordate hallmarks

Question 9

Protochordata

Cephalochordata

Answer 9

• Lancelets
• Bear hallmarks of chordates but in simple form