deuterostomes vs protostomes

• protostomes - Annelida, Mollusca, Arthropoda
  • spiral cell division
  • mesoderm forms near blastospore
  • blastospore >> mouth
  • determinate embryonic development - cell fate fixed early on
• deuterostomes - Echinodermata, Hemichordata, Chordata
  • radial cell division
  • mesoderm forms opposite blastospore
  • blastospore >> anus
  • indeterminate embryonic development - cell fate fixed later in development

phylum Echinodermata - “spiny-skinned”

• level of organization - organ systems
• body symmetry - pentamerous (bilateral larvae, radial adults)
• alimentary structures - 2-hole tube
• triploblastic
• endoskeleton - ossicle bones on inside of organism
  • calcified bones, not chitin
• water vascular system - uses water to move
  • ring canal - surrounds center
  • five radial canals - 1 on each leg
  • madreporite - where water enters
  • ampulla - controls the tube feet that make the organism move
• papula - simple gills that project out into the water
• Class Asteroidea - sea stars
• Class Ophiuroidea - brittle stars, can move w/ legs like cephalopod instead of tube feet

phylum Chordata - “cord”

• level of organization - organ systems
• body symmetry - bilateral
• alimentary structures - 2-hole tube
• triploblastic
• has dorsal hollow nerve cord, notochord, pharyngeal slits, postanal tail
• subphylum Urochordata - tunicates, sea squirts
  • free-swimming larvae have chordate characteristics
  • sessile adults only keep the pharyngeal slits
• subphylum Cephalochordata - lancelets
• subphylum Vertebrata - notochord replaced by bone during development
  • contains fish, amphibians, reptiles, birds, mammals
• Class Agnatha - “w/o jaws”
  • lampreys, hagfishes
  • no jaws, paired appendages
  • cartilaginous skeleton
• Class Chondrichthyes - “cartilaginous fish”
  • sharks, skates, rays
  • cartilaginous skeleton
  • placoid scales
• Class Osteichthyes - “bony fish”
  • gar, bass, coelacanth, perch, etc
  • most diverse vertebrate class
  • air/swim bladder
  • operculum - covers the gills
  • fins - caudal (tail), pectoral (sides), dorsal (top), pelvic (bottom), anal (bottom down, in front of caudal)
• Class Amphibia - “dual life”
  • frogs, toads, salamanders
  • lives on land, but must return to water for fertilization
• Class Reptilia - “to creep”
  • turtles, snakes, lizards
  • has dry skin w/ scales >> better suited for land
  • has amniotic land egg
• Class Aves - birds
  • feathers (replaced scales)
  • forelimbs >> wings
• Class Mammalia - “beast”
  • hair, body fat
  • mammary glands
  • diaphragm to force air into lungs