So that it means that water can flow in one end and come out the other. So if there's anything that's trapped in here like oxygenated water or deoxygenated water or nutrients or something it gets flushed out. The team has come up with computer models to work out how quickly good things, like air and nutrients, move into the burrows. They've estimated the equivalent of a million bathtubs of water flow through every square kilometre of mangrove forest everyday. So the salinity of the soil doesn't go too high.
Crabs like to do spot of house decorating.
They wallpaper the sides of their burrow with leaves, so foul tasting tannin can leach out before they munch into them. It's a firm friendship. Without the crabs and their burrows the mangroves would throw in the towel. So if we're to protect these important breeding grounds for fish and birds - we need to look after the little creatures that call them home. A lowdown on the magic of mangrove ecology from the School of Biological and Environmental Sciences at the Northern Territory University.