Course/Section
Professor/TA
Activity 32.1133.1What can we learn about the evolution of the
animal kingdom by examiningmodern invertebrates?
Fill in the chart on the next two pagesto organize the major characteristics of key
invertebrate phyla.
Activitv 32.1133.1
Copyright@PearsonEducation,Inc., PublishingasBenjaminCummings
195
C)
o (,
!')
(,
oa !,
o
oa
s)
H
(D
oa
t
o
Symmetry?
Cephalization?
True muscle
cells?
Tissueversus
organlevel
development
Numberof
tissuelayersin
embryo
organisms
Examples of
Characteristics
No
Quasi-tissue
level
Doesn't apply
Sponges
Porifera
No; have
epitheliomuscular
cells
Tissuelevel
2; ectoderm
and
endoderm
Cnidaria
Platvhelminthes Nematoda
Annelida
Key invertebratephyla
Mollusca
Arthropoda
Echinodermata
o
o
0a
j
H
(D
c)
oe
a
o
{
!^,
(JJ
P
(J)
.?
o
Other
Type?
Nervous
system?
Ciculatory
system?
Type?
Digestivetract?
Type?
Coelom?
Type?
Characteristics Porifera
Cnidaria Platvhelminthes Nematoda Annelida
Key invertebrate phyla
Mollusca
Arthropoda
Echinodermata
I
II
I
II
I
II
I
I
II
II
I
,t
I
U)
()
o
a
o
o
z
Using the information in the chart and in Chapters32 and 33 of Biology,8th edition,
answerthe questions.
1. What set of characteristics
is sharedby all of the invertebrateanimal phyla in the
chart?
2. What uniquecombinationof characteristics
defineseachof the invertebratephyla as
separatefrom the other phyla?
3. If you comparethe characteristics
of one phylum of the invertebrateswith the nex1.
what key differencesseparatethe groups from each other?
4. a. Looking acrossthe rows, what major trendsappearto occur in the evolutionof
variousorgansor organsystemsin theseanimal groups?
b. What developmentalevidenceis usedto link Annelids,Arthropods,and Molluscs
evolutionarily?
c. what evidenceis usedto separatethe phylain from the Echinodermsand
Chordates?
Activity32.1/33.1
Copyright @ PearsonEducation,Inc., Publishingas Benjamin Cummings
Name
Course/Section_
d. Doesthis analysisprovideevidencefor or againstthe statement:
"Evolutionadds
ontoor modifieswhatalreadyexists"?Explain.
5. The chart organizesthe major groups of animals basedon grade,or sharedbody plan
features. What changeswould you need to make in this organization to reflect the
possible phylogeneticrelationshipsuncoveredusing molecular evidence?To answer
this:
a. On a separatesheet of paper, redraw the chart to reflect the new phylogenetic
relationshipsbasedon molecular evidence.
b. What specific molecular characteristics/dataare being used to determine
evolutionary relationships:rmonganimal phyla?
6. How wouldyour answersto questions2, 3, and4 differ (if at alD whenthe chartis
redrawnandfilled in to reflectchangesin relationshipsbasedon molecular
evidence?
Activity32.1133.1
Copyright @PearsonEducation,Inc., PublishingasBenjaminCummings
r99
1 . In biological terms,a group of organismsis said to be successfulif it is represented
by a large numberof speciesor if the massof all the organismsin the group is large.
(In both cases,"large" is determinedrelativeto other groupsor organisms.)Given
this definition of success,which of the major groupsof animalswould you argueis
the most successful?Be sureto provide evidencefor your argument.
200
Activity 32.1133.1
Copyright @ PearsonEducation,Inc., Publishingas Benjamin Cummings