What needle-like structure provides a skeletal network for a sponge?
a. Cnidoblasts
b. Polyps
c. Spicules
d. Zooxanthellae
ANS: C
Spicules are made of calcium carbonate or silica. They prevent the internal cavities from collapsing.
Spongin, a protein, provides the same function. Information can be found in the section Invertebrates
Are the Most Successful and Abundant Animals.
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Indicate whether the statement is true or false.
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Indicate whether the statement is true or false
Why did Steno propose what eventually became known as the principle of original horizontality?
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The demographic dividend for developing countries typically involves all the following EXCEPT
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