Vertebrates

1
Vertebrates
2
Phylum Chordata

• 4 basic characteristics
• Notochord supporting rod dorsally located,
  below the nerve cord, replaced by vertebral
  column in most chordates
• Nerve cord anterior portion becomes brain, rest
  spinal cord
• Pharyngeal pouches only seen during embryonic
  development, gills in aquatic vertebrates. In
  humans, 1st pair auditory tubes, 2nd tonsils,
  3 and 4th pair thyroid and parathyroid
• Postanal tail in embryo if not in adult

3
Nonvertebrate chordates

• Notochord persists in adults
• Lancelets
• marine, few centimeters long
• retain 4 chordate characteristics as adult
• Sea squirts (tunicates)
• live on ocean floor
• squirt water in defense
• Retain gills as adult

4
Vertebrates

• At some stage in life history, have all four
  chordate characteristics
• Living endoskeleton with vertebral column
• Closed circulatory system
• Paired appendages
• Efficient respiration and excretory
• High degree of cephalization

5
Fishes

• Evolution
• Jawless agnathans, lamprey
• jaws
• Cartilaginous sharks, stingrays
• Bony -
• Lobe finned coelacanths, thought to give rise
  to amphibians
• Ray finned soldier fish, lionfish, seahorse,
  swordfish

6
Fish Characteristics

• Aquatic ectotherms depend on environment to
  regulate body temp
• Skin covered with scales
• Fins for swimming
• Single loop cardiovascular pathway, 2 chambered
  heart
• Breath with gills
• Lay eggs
• Swim bladder seen in bony fish, buoyancy

7
Amphibians

• Live on both land and water
• 3 main groups
• Salamanders and newts elongated bodies, long
  tails
• Frogs and toads - tailless
• Caecilians legless, sometimes sightless, worm
  shaped

8
Amphibian characteristics

• Usually tetrapod 4 legged
• Usually lungs in adults
• Metamorphosis
• Smooth and moist skin
• 3 chambered heart
• Ectothermy
• Most lay eggs in water

9
Reptiles

• Amniotic egg evolves
• Extraembryonic membranes protect the embryo,
  remove nitrogenous wastes and provide the embryo
  with oxygen, food and water
• Crocodiles and alligators, turtles, lizards,
  snakes, amphisbaenians (worm lizards) and tuataras

10
Reptile characteristics

• Usually tetrapods
• Lungs with expandable rib cage
• Leathery-sheled amniotic egg
• Dry, scaly skin that is impermeable to water
• Ectotherms can lay in sun to maintain a warm
  body temperature

11
Birds - Aves

• Some fly, some do not
• Usually classified according to beak and foot
  type
• Efficient nervous, respiratory, and circulatory
  systems.

12
Bird characteristics

• Feathers
• Hard shelled amniotic egg
• 4 chambered heart
• Usually wings for flying
• Air sac
• endothermy

13
Mammals - development

• Monotremes mammals have a cloaca and lay hard
  shelled amniote eggs
• Duckbill platypus and spiny anteater
• Marsupials begin development inside the female
  body and born in a very immature condition, move
  to pouch and attach to nipple
• Kangaroo, koala, wombat
• Placental mammals dependent on the placenta
  (organ of exchange between maternal blood and
  fetal blood)
• Long dependency on the parents

14
Mammal characteristics

• Body hair
• Differentiated teeth
• Well-developed brain
• Usually live births and newborn dependency
• Mammary glands
• Endothermy
• Internal development