Chapter 32 & 33 - Continued

 

Four Critical Innovations of Chordata Body Design

1. Notochord
2. Dorsal, hollow nerve cord
3. Pharyngeal gill pouches
4. Post-anal tail

• These four features are exhibited at some point of life history/development
  • Only some Fishes exhibit all four

Notochord

• Cartilagenous supporting rod along the dorsal axis
• Replaced by jointed "backbone"
  • Vertebral column of hardened cartilage or bone

Dorsal, hollow nerve cord

• Expanded at the anterior end
  • Brian
• Enclosed/supported/protected by the Notocord

Pharyngeal gill pouches

• Gill slits
• pharynx
  • back of mouth cavity

Post-anal Tail

• Tail extends posterior of the anus

Humans