Describe the standard male parental care behavior observed in breeding sticklebacks.

• A. Males build a nest, court females, fertilize eggs externally, guard the brood, and fan water to oxygenate the eggs.
• B. Males incubate eggs in the mouth
• C. Parents share nest duties equally
• D. Young swim freely without parental care

Answer: (A)

In breeding sticklebacks, the male provides comprehensive parental care. He builds a nest, courts a female, and fertilizes the eggs externally as she lays them inside that nest. Once the eggs are laid, the male stays with the clutch, guarding it from predators and fungal infection, and he actively fans water over the eggs to oxygenate them. This combination of nest construction, external fertilization, protection, and aeration is the hallmark of how males care for offspring in sticklebacks.