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31.1 Echinoderms

  • Echinoderms (e.g., starfish) and chordates (e.g., vertebrates) are both deuterostomes.
  • In deuterostomes, the second embryonic opening becomes the mouth, and the coelom develops by outpocketing from the primitive gut.
  • Echinoderms have radial symmetry and a unique water vascular system for locomotion.
  1. What are some of the characteristics of the echinoderms?
    Answer

Essential Study Partner
    Echinoderms

31.2 Chordates

  • All chordates have a notochord, a dorsal hollow nerve cord, and pharyngeal pouches sometime during their life history; in vertebrates, the notochord is replaced by the vertebral column.
  1. What four characteristics must a chordate possess at least some time during its life history?
    Answer

  2. Are all chordates also classified as vertebrates?
    Answer

Essential Study Partner
    Chordates

Art Quiz
    Chordate Features

31.3 Vertebrates

  • There are three groups of fishes. One group is jawless, but the other two groups – the cartilaginous and bony fishes (ray-finned and lobe-finned) – have jaws.
  • Amphibians (e.g., frogs and salamanders) evolved from lobe-finned fishes and have limbs, an adaptation for locomotion on land.
  • The shelled egg of reptiles, which contains extraembryonic membranes, is an adaptation for reproduction on land.
  • Both birds, which can fly, and mammals, which have hair and mammary glands, evolved from reptiles and are able to maintain a constant body temperature.
  1. List the five characteristics that distinguish vertebrates.
    Answer

  2. What evolutionary milestones allowed reptiles to exist fully on land, where amphibians could not?
    Answer

Essential Study Partner
    Introduction
    Fish
    Amphibians
    Reptiles
    Birds
    Mammals

Art Quizzes
    Vertebrate Family Tree
    Evolution of the Jaw
    Evolution of Fishes
    Amniotic Egg of Reptile
    Comparison of Reptile and Fish Circulation
    Placenta

Animation Quizzes
    Evolution of Fish Jaws
    Transition to Land

Case Study
    Sharks Given a Bum Deal by Rumors

31.4 Human Evolution

  • Primates (e.g., prosimians, monkeys, apes, and humans) are mammals adapted to living in trees.
  • Human evolution diverged from ape evolution in Africa about 4 million years ago. The australopithecines were the first hominids.
  • Homo habilis could make tools; Homo erectus migrated out of Africa and was a big game hunter.
  • Cro-Magnon is the name given to modern humans who made sophisticated tools and definitely had a culture.
  1. What characteristics distinguish primates from other mammals?
    Answer

  2. Which primate group is believed to be the most closely related to humans and why?
    Answer

Essential Study Partner
    Primates
    Hominid History

Art Quizzes
    Primate Evolutionary Tree
    Ape and Hominid Skeletons

Case Study
    Why Are We Afraid of Racial Differences?








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