What mechanism does the Cape Cobra utilize during its threat display by spreading its neck ribs?

Spreading its neck ribs to form a hood

When facing a perceived threat, the Cape Cobra engages in a critical defensive behavior involving the musculoskeletal structure of its neck. It actively spreads its neck ribs outward, which results in the formation of the distinctive, intimidating hood. This expansion dramatically increases the snake's apparent size, maximizing the visual impact of its aposematic coloration and the overall threat display. This visual intimidation is paramount to its defense strategy, often succeeding in deterring predators before the necessity of an energetically costly and dangerous strike involving venom delivery.