by Miller & Levine

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Chapter 30

In this chapter, students will read about the general characteristics of chordates and the specific adaptations of two groups of chordates—fishes and amphibians.. The links below lead to additional resources to help you with this chapter.

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Web Codes for Chapter 30:
Science News: Chordates and Vertebrates
SciLinks: Nonvertebrate Chordates
SciLinks: Fishes


Section 30-1: The Chordates
A chordate is an animal that has, for at least some stage of its life, a dorsal, hollow nerve cord; a notochord; pharyngeal pouches; and a tail that extends beyond the anus.
The two groups of nonvertebrate chordates are tunicates and lancelets.

Section 30-2: Fishes
Fishes are aquatic vertebrates that are characterized by paired fins, scales, and gills.
The evolution of jaws and the evolution of paired fins were important developments during the rise of fishes.
Fishes' adaptations to aquatic life include various modes of feeding, specialized structures for gas exchange, and paired fins for locomotion.
On the basis of their basic internal structure, all living fishes can be classified into one of three groups: jawless fishes, cartilaginous fishes, and bony fishes.

Section 30-3: Amphibians
An amphibian is a vertebrate that, with some exceptions, lays eggs in water, lives in water as a larva and on land as an adult, breathes with lungs as an adult, has moist skin that contains mucus glands, and lacks scales and claws.
Early amphibians evolved several adaptations that helped them live at least part of their lives out of water. Bones in the limbs and limb girdles of amphibians became stronger, permitting more efficient movement. A set of lungs and breathing tubes enabled them to breathe air. Their sternum formed a bony shield that supports and protects the internal organs, especially the lungs.
The three groups of living amphibians are salamanders, frogs and toads, and caecilians.






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