Deuterostomes (Ch31)

Developmental Pattern

• Radial, indeterminate cleavage.
  
  

• Blastopore → anus.ffirst

• Coelom forms from mesodermal pouches.
  
  

Echinoderms

• Sea stars, urchins.
  
  

• Pentaradial as adults, bilateral as larvae.
  
  

• Water vascular system, tube feet for movement, gas exchange, feeding.
  
  

Chordates

• Shared traits: notochord, dorsal hollow nerve cord, post-anal tail, pharyngeal slits.
  
  

• Lancelets: Filter feeders, notochord persists.
  
  

• Vertebrates: Backbone replaces notochord, closed circulatory system, large brain.
  
  

Fish Types

• Jawless: Hagfish, lampreys.
  
  

• Jawed (Gnathostomes): Sharks, bony fish. Helped with feed
  
  

• Lobe-limbed fish: Led to tetrapods. Helped with

Tetrapods

• Include amphibians, reptiles, birds, mammals.
  
  

• First vertebrates on land.
  
  

• Amniote egg: protects embryo, allows reproduction without water.
  
  

Reptiles → Birds

• Feathers evolved for insulation, later for flight.
  
  

• Birds are dinosaurs' descendants.
  
  

Mammals

• Sweat glands, mammary glands, hair.
  
  

• Four-chambered heart → efficient circulation.
  
  

• CNS highly developed in humans.
  
  

Human Evolution (in the Primate Group)

5. Humans Evolved Among Primates
   → Humans belong to the primate group – same as monkeys and apes.
   
   

   • We share a common ancestor with chimpanzees.
     
     

   • Over millions of years, humans evolved to walk upright, use tools, speak, and build civilizations.
     
     

6. Central Nervous System Development
   → Mammals, especially humans, have a well-developed central nervous system (brain + spinal cord).
   
   

   • This controls thinking, movement, emotions, and learning.
     
     

   • Human brains are highly advanced, especially for problem-solving, language, and memory.