What distinguishes the soldier caste of Formosan termites?

The soldier caste of Formosan termites is distinguished by their crossed tusks, which are actually elongated mandibles. These mandibles serve as a defense mechanism against predators and are an essential feature for the soldier caste, enabling these termites to protect the colony. Unlike the worker or reproductive castes, soldiers do not have wings, and their primary role is to defend the colony rather than to forage for food or reproduce.

The presence of crossed tusks is a unique characteristic that sets Formosan termite soldiers apart from other termite species and castes, as not all termite soldiers possess this specific morphology. This adaptation is crucial for their survival and illustrates their vital role in the colony's defense strategy.

In contrast, the other options do not accurately describe the defining traits of the soldier caste in Formosan termites. For instance, large wings are associated with reproductive termites, long antennae are a common feature across all castes in termites without distinguishing the soldiers specifically, and bright coloration is not characteristic of Formosan termite soldiers.