Phylum Chordata

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Phylum Chordata

• Chapter 25-26

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Key Terminology

1. Dorsal - back
2. Ventral - belly
3. Endothermic regulate body temp, narrow range
4. Ectothermic temp regulated by environment, wide
   range
5. Oviparous hatch from eggs
6. Ovoviviparous hatch from internal eggs
   (nourished via yolk sac)
7. Viviparous live birth
8. Tetrapod four appendages
9. Notochord skeletal rod
10. Vertebrate - backbone
11. Invertebrate lacks backbone

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1. Characteristics of Chordates

1. Dorsal Notochord
2. Dorsal nerve cord
3. Pharyngeal pouches or gill slits
4. Post anal tail

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1. Subphylum Cephalochordata This subphylum is
   composed of about 2 dozen blade-shaped animals
   known as lancelets. They retain all
   characteristics throughout life.

1. Subphylum Urochordata- This subphylum is commonly
   known as tunicates ( sea squirts). Larva posses
   all chordate characteristics while adults exhibit
   only Pharyngeal pouches.

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2. Subphylum Vertebrata

• All characteristics of chordates
• Distinguishing characteristics
• Vertebral column
• cephalization
• Endoskeleton composed of bone or cartilage
• Bilateral symmetry
• Closed circulatory system

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3. Major groups of Vertebrates
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a. Class Agnathajawless fish

1. Lack jaws
2. Bones
3. ectothermic
4. Lampreys and Hagfishes

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b. Class Chondrichthyes Cartilaginous fish

1. Jaws
2. Paired fins
3. Skeleton of cartilage
4. Gill slits
5. ectothermic
6. Sharks, Skates and Rays

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c. Class Osteoichthyes - boney fish

• Skeleton made of bone
• Operculum and swim bladder
• ectothermic
• All freshwater and most marine fish

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d. Class Amphibia - Dual Life

1. Includes frogs, toads and salamanders
2. tetrapods
3. Skin is moist and permeable to gases and water
4. Most have an aquatic larval stage
5. Gills as larvae, lungs as adults (mostly)

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e. Class Reptilia - to creep or crawl

1. Turtles, crocodiles, alligators, lizards and
   snakes
2. ectothermic
3. Skin is dry and scaly
4. lungs
5. First class not tied to water
6. Oviparous, few ovoviviparous

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f. Class Aves bird

• Adapted for flight
• Feathers
• Hollow bones
• Unique respiratory system
• Endothermic
• oviparous

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G. Class Mammalia Breast

1. Endothermic
2. Hair
3. Completely divided four chamber heart
4. Milk produced from mammary gland
5. Specialized teeth

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1. Order Monotremata

1. Oviparous mammals
2. Most primitive of mammals
3. Only three species

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2. Marsupials

• 250 species, mostly Australian
• The U.S. has only one species the opossum
• Young develop in a pouch, short gestation period

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3. Placental Mammals

1. Mother nourishes the young in uterus via placenta
   (amniotic sac)
2. viviparous
3. 95 of mammals are placental