D

1
Synapomorphies that define the major clades of
the Animal Kingdom
A- Development from a blastula B- Determinant
development with well-developed tissue layers C-
Radial symmetry D- Bilateral Symmetry E-
Blastopore becomes mouth F- Blastopore becomes
anus
D
Acoelomates Pseudocoelomates Eucoelomates
2

• Pseudocoelomate Phyla
• Nematoda
• Nematomorpha
• Acantocephala
• Rotifera
• Kinorhyncha
• Priapulida
• Gastrotricha
• Locifera
• Entoprocta
• Cycliophora

3
Which type of symmetry do protostomes exhibit?
4

• Pseudocoelom ?Persistent blastocoel

5

• Pseudocoelom ?Persistent blastocoel
• Is this a trait that is likely to be primitive?
• Why or why not?

6

• Pseudocoelom ?Persistent blastocoel
• Is this a trait that is likely to be primitive?
  Why or why not?
• Is this a condition that is likely to evolve
  multiple times?

7
http//www.luc.edu/depts/biology/dev/radspirl.htm
8
By definition, in true coelom- mesentery tissue
connects organs to body cavity wall Also, by
definition coelom is fluid-filled body cavity,
found in animals, which is lined by cells
derived from mesoderm tissue in the embryo, and
which provides for free, lubricated motion of
the viscera
9
Figure 1.  The protostomes as separated by Brusca
and Brusca (2003).  This includes two large
clusters the Cycloneuralia and the Articulata
along with several independent clades. BLUE
EUCOELOMATES RED PSEUDOCOELOMATES GREEN
ACOELOMATES
10
Figure 2.  The protostomes as separated by
Nielsen (2001).  This also sets apart the
Cycloneuarlia as a clade.  The cladogram further
sets apart a larger clade that includes the
Articulata of Brusca and Brusca (2003) and the
Mollusca-Sipuncula clade as a coherent group
called the Schizocoela.  BLUE EUCOELOMATES
RED PSEUDOCOELOMATES GREEN ACOELOMATES
11
Figure 3.  A generalized figure (from Tudge 2000)
summarizing the protostomes using molecular
phylogenetics .  BLUE EUCOELOMATES RED
PSEUDOCOELOMATES GREEN ACOELOMATES
12
Figure 4. This is a cladogram of some protostome
phyla modified from Raff (2001).  Note that all
of the pseudocoelomates are missing and that the
Platyhelminthes are considered primitive.  Still,
of the separation of the of the two major
protostome clades falls according to the
Ecdysozoa-Lophotrochozoa hypothesis. BLUE
EUCOELOMATES RED PSEUDOCOELOMATES GREEN
ACOELOMATES
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Radiata and bilateria Well-defined tissue
layers Determinant development
Radiata Bilateria (Protostomes deuterostomes)