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• Phylum Chordata characteristics:

  • Single, hollow nerve cord beneath dorsal surface
  • In vertebrates, it differentiates into brain and spinal cord
  • Notochord: flexible rod on the dorsal side of gut, displaced in vertebrates by vertebral column
  • Pharyngeal slits connect pharynx with outside gills in sharks, fish
  • Postanal tail extends beyond anus, present at least in embryo
• Urochordata (Subphylum Urochordata):

  • Commonly called turnicates
  • Sessile marine animals as adults, motile as larva
  • Larva possess a clear notochord which is less evident in adults
  • Filter feed through use of siphon
• Cephalochordata:

  • Commonly known as lancets
  • Have all features of the ideal chordate
  • Bury themselves in sand, filter-feed through mouth
• Class Agnatha (Jawless Fish):

  • Include hagfish & lampreys
  • Lack paired appendages, poikilothermic
  • Lack bony skeleton, have cartilaginous skeleton
  • Usually have circular sucking mouthparts
• Class Chondrichthyes:

  • Includes sharks, skates, rays, and chimaeras
  • Contain a pair of jaws, most have a heterocercal tail
  • Skin covered by minute tooth-like scales called placoid scales
  • Poikilothermic, lack capacity to regulate internal body temperature
• Class Osteichthyes:

  • Endoskeleton made up of bones
  • Tail is homocercal
  • Contain air bladder for buoyancy, bony dermal scales on skin
  • Poikilothermic
• Class Amphibia:

  • Include salamanders, newts, frogs, toads, and caecilians
  • Many undergo metamorphosis from water to land
  • Characteristics: moist, scaleless skin, cold-blooded
• Class Reptilia:

  • Include alligators, crocodiles, lizards, snakes, turtles
  • Hot-blooded, regulate internal body temperature
  • Scaly skin, absence of hair or fur
• Class Aves:

  • Include flying and non-flying birds
  • Characteristics: feathers, lightweight skeleton, endothermic, lungs with air sacs, beak