While the chemical identity of these alkaloids has been elucidated, their ecological function and the evolution of their biosynthesis remains unclear. The volume, concentration, and apparent effect on the millipedes' predators, such as ants (rapid motor incapacitation), strongly implies a strong deterrent effect. In support of a defensive role, many of the alkaloid-producing millipedes secrete visible secretions from their ozopores (openings of the ozadenes, defense glands) when physically disturbed . This includes the secretion of a white, milk-like substance when collected with forceps (field observations). In addition, there are a few examples of the alkaloids themselves deterring predation experimentally. For example, 1 has been shown to reduce the rate of attack by Formica ants when experimentally applied to mealworms, and polyzonimine (2) produced by Petaserpes rosalbus, is known to act as an insect repellent at concentrations as low as 100 nM . Thus, existing literature strongly supports a defensive role of the terpenoid alkaloid secretions. However, raised the possibility that some of these compounds may also act as pheromones facilitating aggregation, as some members of the subterclass Colobognatha are social millipedes and are known to form aggregates on the undersides of decaying logs .