Body cavity

Acoelomates• FLATWORMS (Phylum _________)• May be the 1st organisms to evolve

organs from mesoderm• Solid, compact body• Organs imbedded in the solid

tissue of the body.• first to have the three cell layers

• Ecto/endo/mesoderm• Have a digestive tract (one way

gut)

Pseudocoelomates• Roundworms (Phylum _________)

• Have a body cavity• It’s fluid-filled and partly lined

with mesoderm• Enables animal to move more

quickly• Muscles attach to the

mesoderm and brace against the pseudocoelom

Coelomates• Segmented worms (Phylum ______)

• Coelom provides space for development of organs/ organ systems

• This allows for membranes like the parietals and viscerals Have a TRUE body cavity

• COELOM= fluid-filled space COMPLETELY surrounded by mesoderm.

• Coelom cushions and protects internal organs and provides room for them to grow and move independently

ANIMAL PHYLA

AB C

1 2

3 4

5 6

7 8

109

Asymmetry

Acoelomates

Pseudo-coelomate Coelomates

This letter represents the asymmetrical animals on the phylogenetic tree

0%

0%

100%

AB C

1. A2. B3. C

This letter represents the animals that exist only at the cellular level of organization.

25%

0%

75%

AB C

1. A2. B3. C

This letter represents the bilateral animals on the phylogenetic tree

83%

17%

0%

AB C

1. A2. B3. C

Based on the tree, the phylum Annelida is most closely related to:

93%

0%0%

7%

AB C

1. Mollusca2. Cnidaria3. Chordata4. Arthropoda

Based on the phylogenetic tree, the term most likely to appear at location “B”

100%0%0%

0%

Pseudocoelomate

AB

1. Radial2. Acoelomate3. asymmetry4. coelomate

Ectoderm Endoderm Mesoderm Coelom

Do You Have A Cavity??? Digestive Tube

Based on the diagrams below, which organism is most likely to store eggs in its coelom?

26%

63%

11%

A B C

1. A2. B3. C