AP Biology Study Guide
Chapter 18: The Evolution of Invertebrate Diversity
Opening Essay
1. Describe the predatory and defensive strategies of the blue-ringed octopus and the mimic octopus.
Animal Evolution and Diversity
2. Describe the defining characteristics of animals.
3. Describe the general animal life cycle and the basic animal body plan.
4. Describe the five-stage hypothesis for the evolution of animals from protists.
5. Describe the Cambrian “explosion” of animal diversity and two hypotheses that have been advanced to
explain its occurrence.
6. Explain how a hydrostatic skeleton helps an animal keep its shape and move.
7. Characterize the nine animal phyla discussed in this chapter in terms of the following traits: (a)
presence or absence of true tissues, (b) no symmetry, radial symmetry, or bilateral symmetry, (c) no
coelom, a pseudocoelom, or a true coelom, and (d) protostomes or deuterostomes.
Invertebrate Diversity
8. Describe the characteristics of and distinguish between each of the following phyla: Porifera, Cnidaria,
Platyhelminthes, Nematoda, Mollusca, Annelida, Arthropoda,Echinodermata, and Chordata. Note
several examples of each phylum.
9. Define segmentation, explain its functions, and note the animal phyla where it occurs.
Compare the characteristics of the four major arthropod lineages. Give examples of each.
10. Describe the common characteristics of insects. Describe the process and significance of complete
metamorphosis.
Animal Phylogeny and Diversity Revisited
11. Compare the phylogenetic relationships in Figures 18.4 and 18.15, noting similarities and differences.
12. Explain what we have learned about the evolution of life from the study of “evo-devo.”
C. Gay 1/5/09
Steamboat Springs High School AP Biology
Key Terms
amoebocyte
annelid
anterior
arachnid
arthropod
bilateral symmetry
bilaterian
bivalve
blastula
body cavity
centipede
cephalopod
chelicerate
choanocyte
circulatory system
closed circulatory system
cnidarian
cnidocyte
coelom
complete digestive tract
complete metamorphosis
crustacean
cuticle
dorsal
dorsal, hollow nerve cord
deuterostome
echinoderm
ectoderm
endoderm
endoskeleton
eumetazoan
exoskeleton
flatworm
fluke
foot
free-living flatworm
gastropod
gastrovascular cavity
gastrula
C. Gay 1/5/09
horseshoe crab
hydrostatic skeleton
incomplete metamorphosis
ingestion
invertebrate
lancelet
larva (plural, larvae)
leech
mantle
medusa (plural, medusae)
mesoderm
metamorphosis
millipede
mollusc
molting
nematode
notochord
open circulatory system
pharyngeal slit
polychaete
polyp
post-anal tail
posterior
protostome
pseudocoelom
radial symmetry
radula
segmentation
sessile
sponge
suspension feeder
tapeworm
tunicate
ventral
visceral mass
water vascular system
Steamboat Springs High School AP Biology