Found only along coastlines in tropical and subtropical areas, mangrove forests have the amazing and unique ability to grow while submerged periodically by brackish, salty water when the ocean’s tide is high. The trees here manage this by growing roots that stick up above the ground and into the air so that gaseous exchange can still take place (in simple terms, the roots ensure the trees don’t 'drown'). 

It might look like an eggplant in a pixie hat, but you're in fact looking at a germinating mangrove seed! The seed begins germinating on the tree and the propagule (the structure that propagates the plant) later falls onto the ground. It's perfectly shaped for sticking in the mud and anchoring itself against the rising tides.

A lifetime of sucking up salty water is not something most plants would manage, but mangroves have a way of dealing with this problem: they concentrate the salt in old leaves, which are discarded onto the forest floor ... where hungry mangrove crabs quickly find them and stash them away in their burrows. 

When temperatures are right and the tides are out, the mud flats will suddenly come alive with movement when thousands of fiddler crabs emerge. These are great creatures to watch as they’re endlessly on the move and waving their claws at each other. To attract mates, males frequently embark on one-upmanship contests to see who's got the best wave with the biggest claw.

The most famous mangrove resident is a land-dwelling fish that's quite comfortable wandering around in the mud amongst the crabs. Mudskippers can skip along with the help of their specially adapted pectoral fins, and (provided they remain wet) can breathe through their skin and mouth lining, like amphibians. They also retain water in enlarged gill chambers, which they shut tightly while on land, keeping the gills moist and oxygenated.

So why would a fish wish to live out of water? Well, who else apart from the crabs does it have to compete with in these intertidal flats that are replenished with silt, nutrients and other tasty tidbits at each high tide? 

Mangroves have proved to be massively valuable in protecting the land from sea-storm surges. In a warming world where ocean levels are rising and storms are becoming more ferocious, it makes sense to protect these areas. This might mean humans have a bit less space, but when the next super storm hits, mangroves could very well save lives. Mangroves also filter out pollutants we throw into our rivers and help to increase fish biodiversity. Not bad for an impenetrable, muddy ecosystem overrun with crabs and walking fish!