Which group has bilateral body symmetry?

Which group has bilateral body symmetry?

• A. Rotifera
• B. Nematoda
• C. Both
• D. Neither

Answer: (A)

Bilateral symmetry means the body can be divided into left and right halves that are mirror images along a single plane, usually with a distinct head end. Rotifera have a body plan where the left and right sides mirror each other along the midline, aligned along a front-to-back axis. Nematoda also show this same pattern: their long, slender bodies are organized so the left and right sides are mirrored across the midline. Since both groups exhibit this symmetry, the correct understanding is that both Rotifera and Nematoda have bilateral symmetry. Choosing that one group has it while the other does not would miss this shared feature, and saying neither group has it isn’t accurate either.

Bilateral symmetry means the body can be divided into left and right halves that are mirror images along a single plane, usually with a distinct head end. Rotifera have a body plan where the left and right sides mirror each other along the midline, aligned along a front-to-back axis. Nematoda also show this same pattern: their long, slender bodies are organized so the left and right sides are mirrored across the midline. Since both groups exhibit this symmetry, the correct understanding is that both Rotifera and Nematoda have bilateral symmetry. Choosing that one group has it while the other does not would miss this shared feature, and saying neither group has it isn’t accurate either.