Which defensive features are typical for ocean-dwelling sticklebacks?

Which defensive features are typical for ocean-dwelling sticklebacks?

• A. Heavy armor with dorsal and pelvic spines
• B. Reduced armor and no spines
• C. Large body size but no armor
• D. Camouflage as the sole defense

Answer: (A)

In sticklebacks, defensive traits shift with habitat due to predator pressures and energy costs. Ocean-dwelling populations keep heavy armor along the sides and prominent spines because these features deter predators in the open marine environment and provide robust, multi-directional protection. The bony plates (armor) resist bites, while dorsal and pelvic spines make it harder for predators to swallow or maneuver the fish. While camouflage can help, it’s the combination of heavy armor and spines that best characterizes ocean populations. The other patterns—reduced armor, large body size with no armor, or camouflage as the sole defense—are more typical of freshwater or different ecological conditions, not the ocean.

In sticklebacks, defensive traits shift with habitat due to predator pressures and energy costs. Ocean-dwelling populations keep heavy armor along the sides and prominent spines because these features deter predators in the open marine environment and provide robust, multi-directional protection. The bony plates (armor) resist bites, while dorsal and pelvic spines make it harder for predators to swallow or maneuver the fish. While camouflage can help, it’s the combination of heavy armor and spines that best characterizes ocean populations. The other patterns—reduced armor, large body size with no armor, or camouflage as the sole defense—are more typical of freshwater or different ecological conditions, not the ocean.