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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. How do deuterostomes differ from protostomes? Answer 2. 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.
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3. What four characteristics must a chordate possess at least some time during its life history? Answer4. Are all chordates also classified as vertebrates? Answer | Essential Study Partner ChordatesArt 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.
| 5. List the five characteristics that distinguish vertebrates. Answer6. What evolutionary milestones allowed reptiles to exist fully on land, where amphibians could not? Answer | Essential Study Partner Introduction Fish Amphibians Reptiles Birds MammalsArt Quizzes Vertebrate Family Tree Evolution of the Jaw Evolution of Fishes Amniotic Egg of Reptile Comparison of Reptile and Fish Circulation PlacentaAnimation Quizzes Evolution of Fish Jaws Transition to LandCase 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.
| 7. What characteristics distinguish primates from other mammals? Answer8. Which primate group is believed to be the most closely related to humans and why? Answer | Essential Study Partner Primates Hominid HistoryArt Quizzes Primate Evolutionary Tree Ape and Hominid SkeletonsCase Study Why Are We Afraid of Racial Differences? |