Predatory red animals use their color to attract curious unsuspecting prey. Regarding the smaller animals, their color serves as a form of aposematic coloration, warning predictors of imminent toxicity.
Their red color warns predators that they are foul to eat. If that doesn’t deter predators, they can play dead and secret a foul-smelling alkaloid from their limbs. They are dependent on aphids for food and help control the aphid population.