Trap-jaw Ants (Odontomachus sp.)
These are some of the fiercest ants in the tropical forest, measuring 3/4 of an inch (2 cm). Their sting packs a wallop, and a related species is called the "bullet ant" because its sting hurts so much.
Trap-jaw ants have huge jaws called mandibles. These jaws will close quickly if touched, and they can hurt small insects and other animals. For humans, the sting is the biggest problem.
You might wonder what the ants are doing on this pretty orange Costus flower. The flower has glands that produce nectar, a sweet drink for the ants. The ants stay on the flower sipping nectar and scaring away any insects that come to harm the flower. The flower gives them food and they protect it. This type of a relationship, where both organisms benefit, is called a mutualism.
Mutualism is very common in tropical rain forests. When a hummingbird pollinates a flower, benefiting the flower, it receives nectar in return. This is a mutualism between the hummingbird and the flower. Mutualisms are very important in the functioning of many plants and animals in the rain forest.