Phylum Cordata

• 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 tunicates
  • Sessile marine animals as adults, motile as larvae
  • Larvae 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
  • Notochord present in embryonic stage and adult life
• Class Chondrichthyes:

  • Includes sharks, skates, rays, chimaeras
  • Contain a pair of jaws, most have heterocercal tail
  • Skin covered by 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
  • Skin covered by bony dermal scales
  • Poikilothermic
• Class Amphibia:

  • Include salamanders, newts, frogs, toads, caecilians
  • Many undergo metamorphosis
  • Cold-blooded, moist, scaleless skin
• Class Reptilia:

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

  • Feathers covering body, wings for flight
  • Lightweight skeleton, endothermic
  • Lungs with air sacs, beak
• Class Mammalia:

  • Share characteristics like mammary glands, hair, 4-chambered heart
  • Orders include Artiodactyla (even-toed hoofed animals) of infra-order Ungulata
• Birds can be classified as either:

  • ARCHEONIRTHES: extinct birds with toothed beak and long lizard-like tail (e.g., Archeopteryx)
  • NEONIRTHES: extant and extinct birds with no teeth and short tail (e.g., Penguin, Pelican)
• All mammals share characteristics like mammary glands, hair, 4-chambered heart, diaphragm, complex brain functions
• Hoofed animals with an even number of toes include those that ruminate and chew cuds, like Girrafidae (giraffes), Cervidae (deer, moose, reindeer, elk), Antilocapridae (pronghorn antelope), and Bovidae (cattle, bison, yaks, etc.)
• Non-ruminating hoofed animals include Suidae (pigs), Tayassuidae (peccaries), Hippopotamidae (hippopotamuses), and Camelidae (camels, llamas)
• Toothed whales include Physeteridae (sperm whales), Monodontidae (narwhals, belugas), Phocoenidae (porpoises), and Delphinidae (dolphins, killer whales)
• Baleen whales are in the family Eschrichtiidae (gray whales), Balaenidae (right whales), or Balaenopteridae (fin-backed whales, hump-backed whales)
• Bats are the only mammals that can fly, with two suborders: Megachiroptera (flying foxes, Old Worm fruit bats) and Microchiroptera (mouse-tailed bats, sheath-tailed bats, etc.)
• Colugos or flying lemurs from Asia, known as Cynocephalidae, are gliding tree mammals that do not fly
• Edentata (toothless mammals) include Dasypodidae (armadillos), Bradypodidae (sloths), and Myrmecophagidae (hairy anteaters)
• Insect-eating mammals in Order Insectivora include Talpidae (moles), Soricidae (shrews), and Erinaceidae (hedgehogs)
• Marsupials in Order Marsupialia include various families like Dasyuridae (native cats, native mice), Phalangeridae (koalas), and Macropodidae (kangaroos, wallabies)
• Egg-laying mammals in Order Monotremata include Tachyglossidae (echidnas) and Ornithorhynchidae (platypuses)
• Odd-toed hoofed animals in Order Perissodactyla include Equidae (horses, donkeys, zebras), Tapiridae (tapirs), and Rhinocerotidae (rhinoceroses)
• Seals and walruses in Order Pinnipedia include Otariidae (eared seals, sea lions), Odobenidae (walruses), and Phocidae (earless seals)
• Primates in Order Primates are divided into Prosimii (tree shrew, lemurs) and Anthropoidae (marmosets, New World monkeys, baboons, gibbons, gorillas, chimpanzees, orangutans, human beings)
• Rodents in Order Rodentia include families like Sciuridae (chipmunks, squirrels), Cricetidae (field mice, lemmings), and Muridae (Old World mice, rats)
• Dugongs and manatees in Order Sirenia belong to families Trichechidae (manatees) and Dugongidae (dugongs, sea cows)
• Aardvarks in Order Tubulidentata belong to the family Orycteropodidae
• Meat-eating mammals in Order Carnivora are divided into Canidae (wolves, dogs), Ursidae (bears, giant pandas), Felidae (cats, lions), Hyaenidae (hyenas), and more
• Commonly called turnicates