1. Animal Evolution and Diversity – Part II
Chapter 18 (end of chapter)

2. Arthropods are segmented animals with jointed appendages and an exoskeleton (not just insects!)
Teaching Tips
Conceptually, and very generally speaking, the exoskeleton of an arthropod is like the hard outside of an M&M. The exoskeleton prevents physical damage to the internal organs and protects them against desiccation. The outside of an M&M prevents damage to the chocolate and keeps the chocolate from oozing out when it melts. (18.11–18.12)
Active Lecture Tips
See the Activity “What Animal Subgroup Do I Belong To? A Twenty Questions Game” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (18.5–18.15)

3. © 2018 Pearson Education, Inc.

4. Echinoderms have spiny skin, an endoskeleton, and a water vascular system for movement
Echinoderms (phylum Echinodermata) are
a diverse group including sea stars, sand dollars, and sea urchins,
slow-moving or ______________,
all marine,
________________ symmetrical as adults, and
deuterostomes (along with the chordates).
Teaching Tips
The bodies of adult echinoderms reveal degrees of radial symmetry, which may cause students to wonder why echinoderms are not grouped with cnidarians. As discussed in Module 18.14, the bilateral symmetry of embryonic echinoderms demonstrates the acquisition of radial symmetry from a bilaterally symmetrical ancestor. Thus, echinoderms are more closely associated with other bilaterally symmetrical organisms. (18.14)
Radial symmetry, such as that seen in many adult echinoderms, permits an organism to respond well in any direction. You cannot sneak up “behind their back.” This ability is especially adaptive in sedentary or relatively sedentary organisms, such as sea urchins, sea stars, and cnidarians. Ask your students if these same advantages also occur in radially symmetrical plants. (18.14)
Active Lecture Tips
See the Activity “What Animal Subgroup Do I Belong To? A Twenty Questions Game” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (18.5–18.15)

5. 18.14 Echinoderms have spiny skin, an endoskeleton, and a water vascular system for movement
an _____________ of hard calcium-containing plates under a thin skin,
a _________ ____________system based on a network of water-filled canals that branch into extensions called tube feet, and
the ability to regenerate lost arms.
Teaching Tips
The bodies of adult echinoderms reveal degrees of radial symmetry, which may cause students to wonder why echinoderms are not grouped with cnidarians. As discussed in Module 18.14, the bilateral symmetry of embryonic echinoderms demonstrates the acquisition of radial symmetry from a bilaterally symmetrical ancestor. Thus, echinoderms are more closely associated with other bilaterally symmetrical organisms. (18.14)
Radial symmetry, such as that seen in many adult echinoderms, permits an organism to respond well in any direction. You cannot sneak up “behind their back.” This ability is especially adaptive in sedentary or relatively sedentary organisms, such as sea urchins, sea stars, and cnidarians. Ask your students if these same advantages also occur in radially symmetrical plants. (18.14)
Active Lecture Tips
See the Activity “What Animal Subgroup Do I Belong To? A Twenty Questions Game” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (18.5–18.15)

6. Video: Echinoderm Tube Feet
© 2018 Pearson Education, Inc.

7. Our own phylum, Chordata, is distinguished by four features
Chordates (phylum Chordata) are defined by
a dorsal, hollow ____________ cord,
a flexible, supportive, longitudinal rod, the __________________,
_________________ slits, and
a muscular post-anal _____________________.
Teaching Tips
If you can obtain a model or image of a one-month-old human embryo, you can demonstrate our four main chordate characteristics. (18.15)
Active Lecture Tips
See the Activity “What Animal Subgroup Do I Belong To? A Twenty Questions Game” on the Instructor Exchange. Visit the Instructor Exchange in the MasteringBiology instructor resource area for a description of this activity. (18.5–18.15)

8. Head Mouth Pharynx Pharyngeal slits Notochord Digestive tract
Dorsal, hollow
nerve cord
Figure 18.15a A lancelet (5–15 cm long)
Water exit
Post-anal tail
Segmental muscles
Anus

9. Post-anal tail Excurrent siphon Dorsal, hollow nerve cord Notochord
Pharyngeal
slits
Mouth
Muscle
segments
Figure 18.15b A tunicate
Adult
Larva

10. Lophotrochozoans: All have a trochophore larva (note-band of cilia)
2 Types of Protosomes
Ecdysozoans: All undergo ecdysis; the molting the outer layer made of chitin.
Lophotrochozoans: All have a trochophore larva (note-band of cilia)

11. You should now be able to
Describe the defining characteristics of animals.
Describe the general animal life cycle and the basic animal body plan.
Describe the Cambrian “explosion” of animal diversity and two hypotheses that have been advanced to explain its occurrence.

12. You should now be able to
Characterize the nine animal phyla discussed in this chapter in terms of the following traits:
presence or absence of true tissues,
two or three embryonic tissue layers,
no symmetry, radial symmetry, or bilateral symmetry,
protostomes or deuterostomes, and
ecdysozoans or lophotrochozoans.
Define segmentation, explain its functions, and note the animal phyla where it occurs.

13. You should now be able to
Compare the characteristics of the four major arthropod lineages.
Describe the common characteristics of insects.
Remember that you have 3 sources for this information:
Lecture ( and these slides)
Textbook ( that you should be reading)
Lab work