chapter 29

• Vertebrates


  Derive their name from vertebrae: the series of bones that make up the backbone
• Vertebrates are the most recognizable organisms of the Animal Kingdom
• 3 groups of terrestrial vertebrates alive today


  • Amphibians
  • Reptiles (including birds)
  • Mammals
• Vertebrates are members of the phylum Chordata, the chordates
• Subphyla of Chordata


  • Urochordata
  • Cephalochordata
  • Vertebrata
• Characteristics of Chordates


  • Notochord
  • Dorsal hollow nerve cord
  • Pharyngeal slits
  • Post-anal tail
• Notochord

  • Flexible rod-shaped structure that runs along nerve chord
  • The notochord develops into vertebrae in vertebrates
• The dorsal hollow nerve cord develops into the spinal cord in vertebrates
• Pharyngeal slits


  • In vertebrate fish, they develop into gill supports.
  • In tetrapods (4 limbed vertebrates), they develop into parts of jaws, ears and tonsils
• Post-anal tail


  Has multiple muscle segments and undulating locomotion
• Vertebrates Endoskeleton

  • have an axial skeleton: skull, vertebrae, ribs
  • have an appendicular skeleton: pectoral and pelvic areas
• The skeletal system and complex nervous system have allowed vertebrates efficiency at capturing food and evading predators
• Vertebrate characteristics


  • Vertebrae made of cartilage and/or bone enclosing the spinal cord
  • Two or more sets of Hox genes
• Chordates: Vertebrates: Cyclostomes


  Jawless vertebrates including hagfish and lamprey
• Cyclostomes(Jawless) general characteristics


  • Reduced vertebrae
  • Eel-like bodies with no lateral fins
  • No jaws
• Gnathostomes


  Jawed vertebrates
• Vertebrates: Gnathostomes(jaw)


  • Hinged jaws derived from skeletal rods supporting gill slits
  • Usually have bony teeth
  • Larger forebrain for smell and sight
• 3 Gnathostome "fish" lineages


  • Chondrichthyes (cartilaginous)
  • Actinopterygii (ray-finned)
  • Sarcopterygii (lobe-finned)
• Gnathostomes: Chondrichthyes (cartilaginous fish)

  • Skeleton of cartilage
  • Most diverse group - sharks, rays, skates
  • few ratfishes or chimaeras
  • bone mineral lost to reduce density
  • buoyancy raised by liver oils and active swimming
  • Bony teeth
  • Most are active predators, marine
  • few filter feed

  
• Chondrichthyes Reproduction: Oviparous


  • internal fertilization
  • Eggs "laid" and hatch outside the mother's body; embryo develops within protective egg-case, fed by yolk
• Chondrichthyes Reproduction: Viviparous

  • with internal fertilization
  • Young develop within the uterus
  • obtain nourishment prior to birth by nutrients from the mother's blood through a yolk sac placenta
  • live birth
• Ovoviviparous


  • with internal fertilization
  • Fertilized egg retained within mother
  • embryo fed by egg yolk
  • live birth
• Gnathostomes: Osteichthyes (bony fish)

  • usually oviparous w/ external fertilization
  • Skeletons remain mostly ossified (mineralized)
  • Flat scales and slime protect and reduce drag
  • Operculum (gill cover) protects and helps pump water over gills
  • Lungs modified into swim-bladder for buoyancy

  
• 2 groups of Osteichthyes


  • Actinopterygii (ray-finned fish)
  • Sarcopterygii (lobe-finned fish)
• Actinopterygii (ray-finned fish)


  • Thin fins supported by long, flexible rays modified for maneuvering, defense etc.
  • Most diverse group of all vertebrates
• Sarcopterygii (lobe-finned fish)


  • Pelvic and pectoral fins supported with bones and muscles
  • Includes coelacanths (actinistia), lungfishes (Dipnoi), and tetrapods

  
• Tetrapods


  • Four limbs with wrist and digits
  • Neck allowing independent head movement
  • Pelvic girdle fused to backbone
  • Lung-breathing as adults (except some aquatic species)
  • Ears for detecting airborne sounds
• Ancestors of Tetrapods

  They were lobe-finned, lung-breathing fish that had many tetrapod features, such as the fossil fish Tiktaalik
• Vic & pectoral fins


  • Supported with bones & muscles
• Lineages of chordates that survive

  • Coelacanths (Actinistia)
  • Lungfishes (Dipnoi)
  • Tetrapods

  
• Cephalochordata

  Basal chordates
• Urochordata

  Basal chordates
• Myxini

  Basal chordates
• Chordates share a common ancestor with Echinoderms
• Vertebrate groups


  • Cyclostomes
  • Petromyzontida
  • Chondrichthyes
  • Actinopterygii
  • Actinistia
  • Osteichthyans
  • Gnathostomes
  • Vertebrae
  • Jaws, mineralized skeleton
  • Lungs or lung derivatives
  • Lobed fins
  • Lobe-fins
  • Dipnoi
  • Amphibia
  • Reptilia
  • Mammalia
  • Tetrapods
  • Amniotes
  • Limbs with digits
  • Amniotic egg
  • Milk
• Amphibia


  • Thin, moist skin; loses H2O easily
  • Gas exchange with air across moist skin & lungs; gulps air like fish to fill lungs
  • Larval stage common aquatic, with gills; metamorphosis into carnivorous adult
  • Almost all are oviparous (fish-like eggs); reproduction is closely tied to fresh water
  • Diverse mating behaviors
• Amniotic egg


  • Reproduction freed from water
  • Amnion protects embryo within watery amniotic sac
  • Other extraembryonic membranes sustain embryo with little water loss
  • Albumen stores water
  • Porous egg-shell protects, reduces water loss but allows O2/CO2 exchange (rigidity varies with amount of CaCO3)
  • Fertilization MUST be internal (before egg shell is made)
• The first amniotes evolved from tetrapod ancestors approximately 340 million years ago during the Carboniferous period
• Amniote groups


  • Synapsids
  • Sauropsids
  • Therapsids
  • Mammals
  • Anapsids
  • Diapsids
• Anapsid Skull

  • no openings behind eyes in skulls