And they can feed from the vast buffet of plants and small creatures encrusting the roots and floating in the rich waters. Snails that move slowly start climbing long before the tide changes so they can reach a safe height by the time the tide comes in. These snails can breathe air. Once a month, the tide is extra high. On these days, these snails don't even come down and instead, climb even higher.
Some crabs also clamber up the trees, some even forage for insects there.
So most of green food is found in the canopy. Many leaf-eaters are thus found in this layer. The mangroves provide additional safety from land-bound predators. Few predators can negotiate the unstable mud and slippery, poky mangrove roots. The thicket of mangrove branches and leaves also provide shelter from strong coastal winds.