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Multiple Choice
Which of the following organisms is a member of the phylum Cnidaria?
A
Jellyfish
B
Octopus
C
Earthworm
D
Sea star
Verified step by step guidance
1
Understand the defining characteristics of the phylum Cnidaria. Members of this phylum are aquatic, mostly marine organisms, and are characterized by radial symmetry, a simple body structure with two tissue layers (diploblastic), and specialized stinging cells called cnidocytes used for capturing prey.
Review the examples of organisms that belong to the phylum Cnidaria. Common members include jellyfish, sea anemones, corals, and hydras.
Analyze the options provided: Jellyfish, Octopus, Earthworm, and Sea star. Compare each organism's characteristics to those of Cnidaria.
Eliminate options that do not match the characteristics of Cnidaria. For example, Octopus belongs to the phylum Mollusca, Earthworm belongs to the phylum Annelida, and Sea star belongs to the phylum Echinodermata.
Conclude that Jellyfish is the correct answer, as it exhibits all the defining traits of the phylum Cnidaria, including radial symmetry and the presence of cnidocytes.