by Miller & Levine

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Chapter 26
Sponges and Cnidarians

In this chapter, you will read about the general characteristics of animals and the structure and function of two of the simplest animal phyla—sponges and cnidarians. You will also learn about the life cycle and major types of cnidarians. The links below lead to additional resources to help you with this chapter. These include Hot Links to Web sites related to the topics in this chapter, the Take It to the Net activities referred to in your textbook, a Self-Test you can use to test your knowledge of this chapter, and Teaching Links that instructors may find useful for their students.

Hot Links Chapter Self-Test
Take it to the Net Teaching Links

What are Web Codes?

Web Codes for Chapter 26:
Active Art: Structure of a Sponge
Data Sharing: Examining the Responses of Hydras
Miller & Levine: Sunscreen from the Sea
SciLinks: Classifying Animals

Section 26-1: Introduction to the Animal Kingdom
An animal is a multicellular, eukaryotic heterotroph whose cells lack cell walls.
Animals are specialized to carry out the following essential functions: feeding, respiration, circulation, excretion, response, movement, and reproduction.
In general, complex animals tend to have high levels of cell specialization and internal organization, bilateral body symmetry, cephalization, and a body.

Section 26-2: Sponges
Sponges are classified as animals because they are multicellular, heterotrophic, have no cell walls, and contain a few specialized cells.
The movement of water through a sponge provides a simple mechanism for feeding, respiration, circulation, and excretion.

Section 26-3: Cnidarians
Cnidarians are soft-bodied, carnivorous animals that have stinging tentacles arranged in circles around their mouth. They are the simplest animals to have body symmetry and specialized tissues.
Cnidarians typically have a life cycle that includes two different-looking stages, a polyp and a medusa.
Cnidarians include jellyfishes, hydras and their relatives, sea anemones, and corals.





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