Above them, on the surface, the mangrove seed floats on its way.
Its chlorophyll means it can photosynthesise, and so remain alive for almost a year, even though it has germinated.
If, during this time, it reaches the fresh water of an estuary, it will run aground in the mud,
grow and create a new mangrove forest on another island of the archipelago.
And with it, new species of animal life also arrive.
One of these is scanning the surface through one of its natural periscopes.
There appears to be no danger. It’s time to come out.
It is a fiddler crab. It’s name comes from it’s enormous claws, almost equal in size as the rest of its body.
The mud of the mangrove swamps is a source of food.
To extract the nutritious substances it contains, the crab scoops it up with its claws, and transfers it to a special organ opposite its mouth.
These organs are equipped with fine hairs which filter out the food, and then place it in the mouth.
The mud left behind is accumulated in a small pellet, and then expelled as the crab moves.
The male can only use one of his claws.
The other is so big that it is useless for collecting mud. The females don’t have this problem
This outsized claw serves two basic functions: to mark his territory, and attract the females.
To do this, the males displays it, with energetic movements.
A rival!
When the female approaches his territory, the suitor tries to get close to her, and draw her into his burrow.
No success this time.
In the end, the females appears to have chosen the other candidate.
If so, they will remain together until they go to the male’s shelter,
where they will mate without being disturbed by the other suitors.
The mangrove forest is home to a number of species of fiddler crabs, but the females have no problem identifying potential mates.
Each species is of a different colour, and performs a different courting dance, which is just as well with so many suitors together.
The enormous number of crabs limits the size of their territories, and increases competition.
It is not rare to see two males at the border between their respective domains fighting for the same female.
With so many suitors together, it is not long before a fight breaks out.
During the mating season, these fierce clashes will be often repeated among all the species of crabs that live in the mangrove forest.
While the crabs get on with their courtship, a tiny animal emerges from the water, supporting itself on its fins.
It is a fish but, nonetheless, does not die from asphyxiation when it comes out onto dry land.