Which statement correctly identifies the function of spines as armor in sticklebacks?

• A. They are modified fins that form dorsal spines and pelvic spines used for defense
• B. They are teeth-like structures used for feeding
• C. They function as fins for swimming only
• D. They are protrusions with no function

Answer: (A)

Spines are modified fin rays that become rigid projections from the dorsal and pelvic fins. In sticklebacks, these hardened spines act as armor, creating a sharp, protective barrier that makes it harder for predators to bite, grasp, or swallow the fish. This defensive role is the primary function, rather than aiding feeding or simply enhancing swimming, and they are certainly not meaningless protrusions.