Millipedes are often misunderstood regarding their potential harm. They are not poisonous, meaning they are not toxic if ingested. Nor are they venomous, as they do not bite or sting to inject toxins. Instead, these arthropods defend themselves by releasing irritating chemical secretions when threatened.
Millipede Defense Mechanisms
When a millipede feels threatened, its primary defense is to coil its body into a tight spiral, protecting its vulnerable underside. Simultaneously, specialized glands along the sides of their bodies, called ozopores, release a defensive liquid. This liquid contains various chemicals designed to deter predators.
The chemical composition of these secretions varies by species but commonly includes compounds like benzoquinones, hydrogen cyanide, phenols, cresols, and hydrochloric acid. These chemical deterrents are effective against a range of predators, including ants, birds, and small mammals, making the millipede unappetizing or irritating to consume.
Contact with Millipede Secretions
Direct contact with millipede secretions can cause skin reactions. Individuals may experience irritation, a burning sensation, and temporary discoloration, often yellow, brown, or mahogany. Benzoquinones in the defensive fluid frequently cause this discoloration. While usually mild, some species cause more pronounced effects like localized redness, swelling, or blisters.
If these secretions enter the eyes, they can cause immediate pain, redness, and temporary visual disturbances like blurred vision. Symptoms such as lacrimation (tearing) and conjunctivitis may also occur. In rare instances, if a curious pet or child ingests a millipede, the chemicals can cause mouth irritation, nausea, vomiting, or stomach upset, though severe poisoning is uncommon. After exposure, promptly wash the affected skin area with soap and water to remove irritants. If eye irritation persists or symptoms worsen, seek medical attention.
Millipedes and Centipedes Compared
Millipedes are frequently confused with centipedes, yet they possess distinct characteristics and defense mechanisms. Millipedes typically have a rounded, cylindrical body shape with two pairs of legs on most body segments. They move slowly and primarily feed on decaying organic matter, acting as decomposers. Their defense relies on coiling and releasing chemical secretions.
Centipedes, conversely, have a flatter body and only one pair of legs per body segment. They are known for their rapid movement and are carnivorous, preying on insects and other small arthropods. Their primary defense is a venomous bite delivered through modified front legs called forcipules. While centipede bites can be painful, causing localized swelling and redness similar to a bee sting, they are rarely life-threatening to humans.