Yellow Crazy Ants 1–0 Red Crabs | 20 Years of Planet Earth II | BBC Earth (Level 1)

Christmas Island is a small island in the Indian Ocean. For millions of years, red crabs have lived there. There are about 50 million crabs. Once a year, the crabs walk to the sea to breed. It is a famous natural event. But now many crabs do not reach the sea. Yellow crazy ants are the problem. They came to the island on ships. The ants have no enemies there, so they spread very fast. When the crabs walk through the forest, the ants attack. They spray acid into the crabs' eyes and mouths. The crabs become blind and confused, and then they die. People brought the ants to the island, so people must now control them. This problem shows that island animals can have big trouble when new dangers arrive.