Subphylum Vertebrata - The Vertebrates

Animals with backbones

1. Vertebrates have all three of the basic chordate features (at least at some stage in life), PLUS....

  • Backbone - the major defining feature of the vertebrates
  • stack of vertebrae
  • dorsal hollow nerve cord (spinal cord) runs down center
  • integrates information coming from various parts of the body
  • communicates information to brain
  • conduit for transfer of information from brain to body
  • Internal skeleton (which backbone is part of)
  • Typical parts (see diagrams of human skeleton in text as example):
  • skull (which encloses and protects brain)
  • vertebral column (discussed above)
  • ribs
  • paired appendages (and associated supporting structures, pectoral and pelvic girdles)
  • Skeletons made of cartilage and/or bone
  • cartilage (made of protein) is firm but flexible
  • bone rigid
  • hardened by calcium phosphate
  • Bones
  • Active, dynamic tissues
  • not like the more static shells of molluscs or skeletons of corals, which grow by secretion of more calcium carbonate on top of older deposits
  • Have lots of blood vessels
  • Bones often hollow inside
  • red marrow - makes red blood cells
  • yellow marrow - fat storage (e.g. in large leg bones)
  • important energy storage in mammals
  • hyenas specialized for cracking bones to get to marrow
  • Hardened by calcium phosphate
  • bones start out as cartilage (protein)
  • calcium phosphate deposited in this protein structure as animal matures
  • Held together by ligaments, connected to muscles by tendons
  • made strong by tough fibrous proteins
  • Complex organ systems
  • complex, but not necessarily more so than organ systems of arthropods, for example
  • most of more complex invertebrates have organ systems somewhat similar to vertebrate systems
  • Vertebrate organ systems include:
  • digestive system
  • complete gut with specialized regions that do different jobs
  • respiratory system
  • gills and/or lungs, depending on species
  • some fish have accessory breathing organs for breathing air
  • typical of species that evolved in stagnant water with low O2
  • these fish can drown if can't come up for air! ...e.g. Siamese Fighting Fish - Betta splendens (see: The International Betta Congress)
  • some amphibians simply use skin for gas exchange
  • no lungs in adults of some salimanders!
  • works because amphibian skin is not watertight and normally is kept moist
  • circulatory system
  • closed circulatory systems
  • heart --> large arteries --> smaller arteries --> capillaries --> small veins --> larger veins --> heart --> etc.........
  • diversity in hearts, including 2 chamber, 3 chamber, and 4 chamber versions
  • excretory system
  • typically involves kidneys in some form or another
  • endocrine system
  • glands and various tissues that send chemical signals through bloodstream
  • help coordinate activities of various parts of body
  • nervous system
  • rapid communication/integration of activities among different parts of body
  • skeletal system
  • structural support
  • muscular system
  • provides movement
  • reproductive system

    • 2. Major classes of vertebrates:

  • Class Agnatha - the jawless fish (lampreys and hagfish)
  • Hagfish
  • deep sea creatures
  • feed on dead animals (get inside and eat from inside out!) and small invertebrates in sediments
  • Hagfish photos and information can be found at several websites:
  • OceanLink: OceanInfo - The Hagfish Page
  • The Lowly Hag (at the bottom of this page there's a link to a movie showing hagfish in action!)
  • Lampreys
  • many species parasitic/predaceous on fish
  • larvae are filter feeders
  • sea lamprey entered Great Lakes via St. Lawrence Seaway
  • wrecked havoc with fish populations
  • Interesting lamprey web sites:
  • SEA LAMPREY (informative site)
  • Welcome to the Sea Lamprey Fishtank (nice photos to look at)

  • Class Chondrichthyes - cartilaginous fish (sharks, rays, and others)
  • Except for teeth, skeleton entirely cartilaginous
  • Mostly marine, but some in freshwater
  • some sharks come into freshwater
  • some come as far north in Mississippi River as southern Illinois
  • Lake Nicaragua has resident population of sharks (this species normally lives in ocean)
  • numerous species of freshwater stingrays in Amazon river system.
  • Familiar animals, even in popular culture
  • Lots of myths about sharks - e.g. not all are large and dangerous
  • Discussed in "Life on Earth" video in lab
  • Class Osteichthyes - bony fish
  • The most diverse group of vertebrates by far!
  • over 18,000 species!
  • in contrast, only about 8600 species of birds, and 4100 species of mammals
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  • MORE TO COME ON BONY FISH AND OTHER VERTEBRATES BELOW
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  • Class Amphibia - the amphibians (frogs, toads, salimanders, newts, and others)
  • Class Reptilia - the reptiles (turtles, crocodilians, snakes and lizards, and others)
  • Class Aves - the birds (some folks now classify birds in the same group as the otherwise extinct dinosoaurs)
  • Class Mammalia