Mexican frogs literally use their heads for survival.
They have bony crests or bumps on their heads
which they use as tight fitting doors to seal their homes.
During droughts they move into the trunks of trees
or into holes in plants of pineapple family.
Once inside the hole, the frog plugs the entrance
with its head and sits out the drought.
The bony helmet loses very little water.
The seal ensures that the frog and its hole remain
comfortably moist throughout the drought.
Amazing Animal Kingdom 