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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?

2. What are some of the characteristics of the echinoderms?
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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.
3. What four characteristics must a chordate possess at least some time during its life history?

4. Are all chordates also classified as vertebrates?
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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.
5. List the five characteristics that distinguish vertebrates.

6. What evolutionary milestones allowed reptiles to exist fully on land, where amphibians could not?
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Art Quizzes
Vertebrate Family Tree
Evolution of the Jaw
Evolution of Fishes
Amniotic Egg of Reptile
Comparison of Reptile and Fish Circulation

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.
7. What characteristics distinguish primates from other mammals?

8. Which primate group is believed to be the most closely related to humans and why?
Essential Study Partner
Hominid History

Art Quizzes
Primate Evolutionary Tree
Ape and Hominid Skeletons

Case Study
Why Are We Afraid of Racial Differences?

Inquiry into LifeOnline Learning Center with Powerweb

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