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Vertebrate Structure and Function Part 1 - Comparing Structure and Function

Classification of Vertebrates a.  Phylum: Chordata Common Characteristics: Notochord, pharyngeal gill slits, hollow

dorsal nerve cord

b. Sub-phylum: Vertebrata Common Characteristics: Backbone that supports and protects

spinal cord, endoskeleton, distinct head with skull and brain

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Part A: Overview of Vertebrate Classes 1.  Vertebrate Class Definitions

a.  Fish - aquatic vertebrates that are characterized by scales, fins and pharyngeal gills. There are 3 main groups: jawless, cartilaginous and bony. Ex. Lamprey, dogfish shark, perch.

b.  Amphibians - vertebrates that are aquatic as larvae and terrestrial as adults. They breathe with lungs as adults, have a moist skin with glands and lack scales and claws. Ex. Frog, salamander, newt.

c.  Reptiles - vertebrates that have lungs, scaly skin and a special type of egg (amniotic). They live entire life out of water. Ex. Snake, lizard, turtle.

d.  Birds - endothermic, reptile-like vertebrates with feathers, two legs used for walking and perching and wings that usually don’t have claws. Ex. Pigeon, hawk, eagle.

e.  Mammals - endothermic animals with fur or hair, and mammary glands that produce milk to nourish young. Almost all give birth to live young. Ex. Human, whale, fetal pig.

Part B: Important Evolutionary Advances a.  Jaws in Fishes

•  Fish are considered to be the most primitive living vertebrate.

•  The first fishes to be found in abundance in the fossil record were jawless. These are limited to eating small particles of food by filter-feeding and vacuum suction.

•  The evolution of jaws in fishes made it possible for them to eat plants and other animals and defend themselves by biting.

b.  Strength of Skeleton in Amphibians

•  Amphibians probably evolved from �lobe-finned fishes. These organisms �faced many challenges transitioning �from water to land.

•  The first amphibians had strong �limb bones and girdles for �movement unsupported by water.

•  The ribs formed a cage that �supports and protects the internal �organs.

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c. Eggs in Reptiles

•  Reptiles evolved from amphibians when climatic changes caused destruction of amphibian habitat. These organisms had to survive their entire lives on land.

•  Reptilian eggs are surrounded by a shell and several membranes that create a protected environment for the embryo.

•  These “amniotic eggs” contain nutrient-rich yolk used by the embryo for food.

d. Temperature Control in Birds and Mammals

•  Fish, amphibians and reptiles are ectothermic. The have an internal body temperature that varies with external (environmental conditions) due to a slow metabolism.

•  Birds and mammals are endothermic. They maintain a relatively high and constant internal body temperature that is regulated internally due to a fast metabolism.

•  This adaptation is very important for animals living in habitats where temperatures and seasons are variable.

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Part C: Comparing Structure and Function Among Vertebrates

  Feeding and Digestion

a.  Jaws and Teeth

Part C: Comparing Structure and Function Among Vertebrates

  Feeding and Digestion

a.  Jaws and Teeth

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  Feeding and Digestion

b. Digestive Systems

  Respiration

a. Lungs

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  Respiration

Fish

  Circulation/Internal Transport

a.  Heart Chambers and Circulatory Systems

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  Reproduction

a.  Definitions

•  Oviparous: a vertebrate that lays eggs that develop outside the mothers body

•  Ovoviviparous: a vertebrate whose young develop inside the mother’s body but are not nourished directly by the mother’s body.

•  Viviparous: a vertebrate who bears live young and directly nourishes the unborn young by the mother’s body.

b. Fertilization

•  External: eggs are fertilized outside the mother’s body.

•  Adults release eggs and sperm into the surrounding water and sperm swim to the eggs to fertilized them.

•  To increase chances, huge numbers of eggs and sperm are released.

•  Internal: eggs are fertilized inside the mother’s body.

•  Sperm is deposited into the body of the female.

•  This makes it possible for the female’s reproductive system to cover the embryos with protective membranes and a shell after fertilization.