Which term is a phylum of marine invertebrates that includes starfish and sea urchins?

Which term is a phylum of marine invertebrates that includes starfish and sea urchins?

• A. Echolocation
• B. Echinodermata
• C. Gastropoda
• D. Gill Membranes

Answer: (B)

Classification of marine invertebrates by phylum is what this question tests. Starfish and sea urchins belong to the phylum Echinodermata, a group composed almost entirely of marine animals that share key traits. They display pentaradial symmetry as adults, have a water vascular system with tube feet for locomotion and feeding, and possess a calcareous internal skeleton. These characteristics distinguish echinoderms from other invertebrate groups. Echolocation isn’t a taxonomic group but a sensory method used by some animals. Gastropoda is a class within Mollusca (snails and slugs), not starfish or urchins. Gill membranes are anatomical structures, not a phylum. Therefore, the correct designation is Echinodermata.

Classification of marine invertebrates by phylum is what this question tests. Starfish and sea urchins belong to the phylum Echinodermata, a group composed almost entirely of marine animals that share key traits. They display pentaradial symmetry as adults, have a water vascular system with tube feet for locomotion and feeding, and possess a calcareous internal skeleton. These characteristics distinguish echinoderms from other invertebrate groups. Echolocation isn’t a taxonomic group but a sensory method used by some animals. Gastropoda is a class within Mollusca (snails and slugs), not starfish or urchins. Gill membranes are anatomical structures, not a phylum. Therefore, the correct designation is Echinodermata.