Phylum Chordata

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Phylum Chordata
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SUBPHYLUMS Three Types

• 1 Urochordata (Tunicates and Seaquirts)
• Considered as the invertebrate chordata
• As an adult they have an reduced nervous system
  and loss notochord
• No definite head
• Filter feeders

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• 2 Cephalochordata (lancelets)
• Also a invertebrate chordata-only 29 species
• Filter feeders with cilia to carrier particles
  into their mouths
• 3 Vertebrata (vertebrates)
• Roughly 43,000 species
• Have vertebral column and a backbone that is the
  supporting axis holding up the body and
  protecting the spinal cord

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Chordata Classes

• 1 Agnathans (Agnatha) jawless vertebrates
  (lampreys and hagfish)
• 2Chondrichthyes-cartilaginous fish (sharks,
  skates, rays, and chimaeras)
• Have teeth and small scales
• Have separate gill openings
• 3Osteichthyes Bony fish
• Bony skeletons and jaws

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• 4 Amphibia (Amphibians) (Frogs, Toads,
  salamanders, and newts)
• Live near or in fresh water
• Four-legged except Order Apoda-legless
• Life cycle tadpole adult and most undergo
  metamorphosis when changing into an adult

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• 5 Reptila Reptiles (turtles, tortoises,
  tuatara, snakes, lizards, alligators, crocodiles,
  and caimans)
• Evolved from primitive amphibians
• Ones with legs, are usually stronger and larger
  than amphibians, enable many reptiles to carry
  their bodies off the ground
• Lungs better developed than amphibians, and have
  larger rib muscles allowing for better lung
  ventilation
• 4 chambered heart and most are cold blooded
• Lay eggs that include both the shelled egg and
  the embryonic membrane amnion (amphibians lack)
• Internally fertilized

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• 6 Aves Birds
• 4 chambered heart but warm-blooded
• Simple excretory system, highly developed brain,
  and respiratory system
• Lack teeth, and the bones are hollow (light for
  flight)
• All have feathers and many fly and lots of birds
  migrate
• Internal fertilization
• Lay eggs with calcium carbonate shells, after
  development they peck at the shell with an egg
  tooth that cracks the shell so the chicks become
  free

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• 7 Mammalia Mammals
• Evolved from an early group of reptiles
• Warm-blooded and have a 4 chambered heart
• Have hair and fur for insulation, also layers of
  fat or blubber under their skin for warmth
• Have a diaphragm, the muscle under the rib cage
  that reptiles do not have improves breathing
• Sweat glands help regulate the body temperature
  and rid body of wastes
• Scent glands produce chemical substances that
  help mammals communicate with each other
• Most have highly developed teeth

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• Mammalia continued
• Specific skeletal features are unique, such as an
  enlarged cerebrum
• Reproduce by internal fertilization
• Only the Order Monotremes lay eggs, most give
  birth to young and nourish them by milk produced
  in mammary glands of the female

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Orders of Class Mammalia

• 1 Monotremata Montremes
• 2 Marsupalia Marsupials
• 3 The Placental Mammals (several orders)