General Characteristics

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General Characteristics
Phylum Chordata

• Have a notochord. What does this form?
• Have dorsal hollow nerve tube. What does this
  form?
• Have pharyngeal gill slits. What happens to
  these?
• Have tails at one point in their development.

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Embryonic Comparison
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II. Classification

• A. Subphylum Cephalochordata
• 1. Lancelets

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II. Classification

• B. Subphylum Urochordata
• 1. Sea Squirts (Tunicates)

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II. Classification

• C. Subphylum Hemichordata
• 1. Acorn Worms

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II.Classification

• D. Subphylum Vertebrata
• Characteristics
• Have a backbone (spinal column)
• Have endoskeleton made of calcium phosphate.
• Two major groups of vertebrates ectotherms and
  endotherms.

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IV. Ectothermic (Cold-blooded) Classes

• Class Agnatha (Jawless fish)
• Skeleton made of cartilage.
• No scales with tubular body.
• Lack paired appendages. e.g. lampreys and hagfish

• Class Chondrichthyes
• Skeleton made of cartilage, e.g. Rays, Skates
  and Sharks
• Lack gill covers (opercula) and swim bladders.
• Have placoid scales

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C. Class Osteichthyes

• Skeleton is made of bone e.g. trout, bass,
  salmon, sole etc.
• Gills with opercula for protection and to move
  water over gills.
• Have cycloid scales.
• Most common fish class.

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D. Class Amphibia (means dual life)

• 1. Smooth skin and lack claws e.g. frogs, toad,
  newts and salamanders.
• 2. Evolved from fleshy-lobed fish (Coelocanth)

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E. Class Reptilia

• 1. Dry (water proof), scaly skin with claws.
• 2. Evolved from amphibians
• 3. Snakes, lizards, turtles, crocodiles and
  alligators

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V. Problems with transition to land

• Drying out.
• Too heavy. Why?
• Extreme temperature changes.
• Respiration - why dont gills work on land?
• Reproduction
• How to get egg sperm together?
• How do chordates prevent their eggs from drying
  out?

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VI. Adaptations to land

• Waterproof skin coverings scales, feathers and
  fur.
• Appendages move more ventral as opposed to
  lateral placement.
• Lungs replaced gills
• Amniotic eggs with internal fertilization.
• -Evolved first in reptiles

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D. Amniote Egg Water Tight but permeable to
oxygen. 1. Chorion - used for respiration
2. Allantois - stores liquid wastes
3. Amnion - filled with fluid for a cushion
4. Yolk Sac - stores food (yolk)
5. Embryo
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2
3
1
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VII. Endothermic (homeothermic) Classes

• What is the advantage of being homeothermic?
• Can live in cold environments or cold nights.
• B. What is the source of heat?
• 1. Muscles contraction
• C. Which body systems must adapt to be
  endothermic?
• A. Digestive system Why?
• Respiratory system Why?
• Circulatory system Why?
• Integumentary Why?

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D. Class Aves

• 1. Body covered with feathers
• 2. Have wings and beaks with no teeth.
• 3. Have hollow bones
• 4. All birds are oviparous.
• 5. Evolved from reptiles-Archaeopteryx

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E. Class Mammalia

• Body covered with hair
• Nurse young with mammary glands
• Warm blooded
• Give birth to live young
• Evolved from reptiles.

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VIII. Movement

• Fish
• Fins used to stabilize and move fish through
  water
• Fish are streamlined to move easily through the
  water.
• Swim bladders filled with oil or gas to help fish
  float in the water.

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Movement (cont)

• Amphibians, reptiles and mammals
• Most use four muscular limbs, to hop, walk and
  run on land.
• Limbs gradually moved from the side to under an
  animal.
• Snakes and legless lizards use large scales
  called scutes on ventral surface.

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VIII. Movement (cont)

• Birds
• Wings and feathers
• What was the original function of feathers?

Quill
Contour
Down
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Movement (cont)

• Birds
• 3. Adaptations for flight
• Forearms modified into wings with feathers.
• Hollow bones with modified skeleton for muscle
  attachment and flight movement.
• Air sacs throughout make them less dense and
  ready supply of oxygen.
• Excretory wastes are crystalized combined with
  digestive waste. Why?

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IX. Feeding

• Most have teeth and were the first animals to
  have a hinged jaw (except jawless fish).
• Types of food depend on the species herbivores,
  carnivores, omnivores, parasites, and scavengers.

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Hinged Jaw Evolution
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X. Protection

• Flight, schooling, camouflage, poison, spines,
  teeth, etc.
• Scales
• Feathers, fur and fat help insulate.

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XI. Digestion

• Highly specialized system with associated organs
  like the liver, pancreas, and gallbladder.

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XII. Circulation

• Closed circulatory system with different hearts.
• Fish have a 2-chambered heart.

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• Amphibians most reptiles have a 3-chambered
  heart.
• Birds and mammals have a four chambered heart.
• What is the problem with a three chambered heart?

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Circulation

• Birds mammals have a 4-chambered heart.

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XIV. Respiration

• Fish use gills.
• Reptiles, birds and mammals use lungs.

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Respiration

• Amphibians use small lungs, but mostly through
  their skin.

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XV. Excretion

• All use kidneys
• Consisting of millions of nephrons.
• We will study the structure and function of a
  kidney when we study the human body..
• Problems with water balance
• Marine fish have salt-removing structures in
  gills that actively transport salt out of them.
• Marine birds and reptiles secrete excess salt
  through specialized glands.
• Fresh water animals are more waterproof and more
  active kidneys.

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Overall Excretory System
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XVI. Nervous

• All have complex systems.
• Cerebral cortex increases from fish to mammals.
• This area is associated with higher functioning,
  so what does the above statement mean?

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Brain evolution
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Nervous
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XVII. Reproduction

• Some are oviparous
• Lay eggs which hatch and develop outside of
  mothers body
• Some are ovoviviparous
• Eggs hatch inside mother and give birth to live
  young, but no nourishment provided by mother.
• Some are viviparous
• Bear live young, which are nourished by mother.