Vertebrates in the Sea

1
Vertebrates in the Sea on Land

• Section 32.1

2
Adaptations of Vertebrates

• Chordates with a backbone
• Made of vertebra segments
• Completely replaces the notochord
• Provides a site for muscle attachment and
  protection of the spinal cord
• Allows for a bony skull to enclose and protect
  the brain
• Segmentation
• Bilateral symmetry
• Two pairs of jointed appendages
• Cephalization
• A true coelom
• Closed circulatory system with a chambered heart

3
The First Vertebrates

• First appeared about 500 million years ago
• Lived in water
• Agnathans early fish without jaws or paired
  fins
• Evolution of fish involved
• Improved swimming flattened bodies became
  streamlined paired fins for control
• Development of jaws from gill arch supports
  made of cartilage

4
Modern Fish

• More fish species than any other vertebrate
• Three groups
• Agnathans jawless fish hagfish lampreys
• Cartilaginous fishes skeleton of cartilage
  sharks, skates rays
• Bony fishes skeleton of bone (95 of all fish
  species)

5
Agnatha lampreys hagfish
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Cartilagenous fish Sharks, skates, rays
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Bony Fish most fish are in this group
8
Evolution of Amphibians

• Appeared about 370 million years ago
• Name means double life they live in water as
  juveniles and on land as adults
• Adaptations to land include
• Legs support body allow movement
• Lungs do not need as much water to function
• Heart walking on land requires more energy and
  therefore a stronger pump

9
Three Groups of Modern Amphibians

1. Frogs toads largest group
2. Salamanders newts
3. Caecilians less than 1

10
Frogs have smoother skin than Toads
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Salamanders Newts
12
Caecilian