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Unformatted text preview: tly evolved traits. Clicker Question 3. Pick the best answer.
Based on the phylogeny presented in the most recent
edition of your textbook (Life, 9th Edition), most features
that are characteristic of sponges are likely to represent:
But recent genomic studies (e.g., Philippe et al. 2009 Current
Biology 19: 706-712) strongly support monophyly of sponges
(tree B). These results are reflected in the most recent of your
textbook (Life, 9th Edition). a.
d. Eumetazoan synapomorphies.
Synapomorphies of the sponges.
Ancestral metazoan conditions.
Convergently evolved traits. A = demosponge
B = glass sponge
C = calcareous sponge 4 Sponges
- Differentiated cell types (no true tissues/organs)
- Gelatinous matrix (mesohyl) w/ collagen
- Spicules (skeletal elements Aquiferous system - water flows continuously into
incurrent pores (ostia), traverses internal chambers,
and exits out of excurrent pores (oscula) Sponge features • Asymmetrical gutless animals
• Aquiferous system: branched water canals
• Differentiated cell types but no true tissues or organs
• Cells arranged in gelatinous matrix (mesohyl) with
collagen and usually spicules (skeletal elements) Flagella helps bring in water and collect
food Aquiferous system: water flows continuously into numerous
incurrent pores (ostia), traverses internal chambers, and exits
out of one or more excurrent pores (oscula); propelled by
movement of flagella of many choanocy...
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- Spring '09