For those who've made it this far, a more horrible fate awaits. Yellow crazy ants, aliens accidentally introduced by cargo ships. Now super colonies of billions terrorize the migrating crabs. The ants attack, spraying acid into their mouths and eyes, blinding them, leaving them helpless. In the 1990s, the crazy ants slashed the crab population by a third, from 80 million to 50 million. 

 

Beyond the ants lies a dizzying descent, 40 feet, straight down to the beach. Now the males face the waters of their birth. They dip into the ocean to restore their bodies with salts and moisture. But these land crabs are air-breathers. And the Indian Ocean plays no favorites with her prodigal sons.