Which term refers to the phylum that includes sea stars, sea urchins, and sea cucumbers?

Which term refers to the phylum that includes sea stars, sea urchins, and sea cucumbers?

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

Answer: (A)

Sea stars, sea urchins, and sea cucumbers all belong to the same phylum, Echinodermata. This group is defined by a calcareous internal skeleton (endoskeleton), a water vascular system that powers tube feet used for movement and feeding, and typically radial symmetry as adults (often in a five-point pattern). They are marine invertebrates, and their development is deuterostome, with larvae that are bilaterally symmetrical before becoming the characteristic radial form. Other options don’t fit as a phylum for these animals: Gastropoda is a mollusk class that includes snails and slugs; echolocation is a sensory process seen in some animals, not a phylum; gill membranes are structures related to respiration, not a taxonomic grouping.

Sea stars, sea urchins, and sea cucumbers all belong to the same phylum, Echinodermata. This group is defined by a calcareous internal skeleton (endoskeleton), a water vascular system that powers tube feet used for movement and feeding, and typically radial symmetry as adults (often in a five-point pattern). They are marine invertebrates, and their development is deuterostome, with larvae that are bilaterally symmetrical before becoming the characteristic radial form.

Other options don’t fit as a phylum for these animals: Gastropoda is a mollusk class that includes snails and slugs; echolocation is a sensory process seen in some animals, not a phylum; gill membranes are structures related to respiration, not a taxonomic grouping.