Vertebrates

Chapter 34

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4 Chordate Characteristics

1. Notochord Long, flexible rod between digestive tube and nerve cord NOT the spinal cord

2. Dorsal Hollow Nerve Chord Formed from ectoderm

3. Pharyngeal Clefts (Gills) Pouches along side of pharynx

4. Post-anal Tail Do I need to explain this one?

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Chordata NOT Vertebrata Classes

Cephalochordata Lancelets

Urochordata Tunicates

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Vertebrate Classes

Agnathasomes

Fishes Chondrichthyes Osteichthyes

Amphibia

Reptiles

Birds

Mammals

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Vertebrate Classes

Lampreys & Hagfish (Agnathostomes) Oldest vertebrates Jawless, parasitic, cartilaginous skeleton

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Chondrichthyes

Cartilaginous Fishes (Chondrichthyes) Cartilaginous skeleton Sharks & Rays

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Osteichthyes

Bony fishes

Bony exoskeleton

Swim Bladder

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Amphibia

Frogs and salamanders

Gas exchange occurs across the thin, moist skin

External fertilization & external development in an aquatic environment

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Amniotes

Terrestrial tetrapods with terrestrially-adapted egg

Reptiles, Birds (Aves), and Mammals

Amniotic Egg Adaptation to living on land (especially dry land) Shell that retains water

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Amniotic Egg

4 Extra embryonic Membranes:1. Amnion – encloses the embryo in fluid sac Shock absorption Amniotic fluid

2.Chorion & Allantois – Gas exchange3.Allantios – disposal sac for metabolic wastes4.Yolk Sac – contains the yolk (nutrient stockpile)

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Reptilia

Turtles, lizards, snakes, alligators, & dinosaurs

Keratin-containing scales - Reduce water loss

Lungs for obtaining oxygen

Internal fertilization (cloacal kiss)

Uric Acid – nitrogenous waste

Amniotic egg

Ectothermic – control body temp. through external means

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Birds

Wings

Reptilian Characters Amniotic egg Leg scales with keratin

Adapted for flight Light, hollow bones Few organs Feathers

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Birds (Page 2)

Endothermic Maintain warm, consistent

body temperature Feathers + fat layer insulate

birds High rate of metabolism

4-Chambered heart

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Mammal Characteristics

Milk

Mammary glands – produce milk

Body covering of fur or Hair

Internal fertilization Most are born rather than

hatched

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Mammal Types

Monotremes Egg-laying mammals Have hair & produce milk

Marsupials Born early & complete development

in marsupium (pouch) while nursing

Eutherians (Placental mammals) Long pregnancy period Development proceeds inside uterus

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Primates

Order that contains humans, monkeys, & gorillas

Opposable thumbs

Large brains

Forward-oriented eyes

Intensive child rearing

Complex social structure