User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-11075144-20130727180927/@comment-4009941-20130728050545

Let me assist you in the oxygen theory since I know info about their beard

Ceadeus keep speciel algae in their beard that continues to grow and spread as they age, they use this algae to breath underwater as it provides Oxygen while they provide it Carbon Dioxide and a home. At the same time the glowing spots on Ceadeus are Luminecent Bacteria that assist in photosynthesis for growing the algae. Using this average Ceadues are able to stay underwater for days at the ocean floor.

I t is said that Goldbeard Ceadeus have enough algae and bacteria to stay underwater and not come back to the surface. If Goldbeard is another species or old member of the same is unknown.

Official Ecology info if you hate it blame Capcom not me.