Which life stage of cnidarians is free-swimming and bell-shaped?

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Multiple Choice

Which life stage of cnidarians is free-swimming and bell-shaped?

Explanation:
Cnidarians have two main life forms: a sessile polyp and a free-swimming medusa. The free-swimming, bell-shaped form is the medusa, which uses pulsations of the bell to propel itself and capture prey, as seen in jellyfish. The polyp, by contrast, is attached to a surface and typically vase- or tube-shaped, not free-swimming. A planula is a free-swimming larval stage that will settle as a polyp (or develop into a medusa in some groups), so it isn’t characteristically bell-shaped. Cnidaria refers to the whole phylum, not a life stage.

Cnidarians have two main life forms: a sessile polyp and a free-swimming medusa. The free-swimming, bell-shaped form is the medusa, which uses pulsations of the bell to propel itself and capture prey, as seen in jellyfish. The polyp, by contrast, is attached to a surface and typically vase- or tube-shaped, not free-swimming. A planula is a free-swimming larval stage that will settle as a polyp (or develop into a medusa in some groups), so it isn’t characteristically bell-shaped. Cnidaria refers to the whole phylum, not a life stage.

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