Question

1. which trait is characteristic of vertebrates?

they have radial symmetry.
they have exoskeletons.
they have no defined organ systems.
they have well - defined skeletons.

Explanation:

• Radial symmetry is typical of cnidarians (e.g., jellyfish), not vertebrates (vertebrates have bilateral symmetry).
• Exoskeletons are found in arthropods (e.g., insects), while vertebrates have endoskeletons.
• Vertebrates have complex, defined organ systems (like circulatory, nervous systems).
• Vertebrates have well - defined internal skeletons (endoskeletons) made of bone or cartilage, which supports the body and protects organs.

Answer:

D. They have well - defined skeletons.