Millipedes belong to the class Diplopoda, a group of arthropods that are not insects, but are related to centipedes. They are often mistaken for pests, but they are detritivores that break down decaying plant matter like leaf litter and rotting wood, enriching the soil with nutrients. The name “millipede” translates to “a thousand feet,” though most species possess far fewer, with each body segment bearing two pairs of legs. Determining a millipede’s lifespan is complex because it is highly variable, ranging from a few years for smaller species to over a decade for some larger, commonly kept species.
General Lifespan of Millipedes
The typical longevity for most millipede species ranges from two to seven years in their natural environment. Smaller species, such as those found in temperate climates, often live for the shorter duration of two to three years. This relatively long life for an invertebrate suggests a slow life cycle and a robust defensive strategy, primarily involving coiling into a tight ball and possessing a hard exoskeleton.
Larger millipedes, particularly those native to tropical regions, frequently occupy the upper end of this spectrum. The Giant African Millipede (Archispirostreptus gigas), for example, can live between five and seven years in the wild. Many larger Diplopoda species have the potential for an extended life, with some individuals surviving for ten years or more in optimal conditions.
The Millipede Life Cycle
The journey from egg to adult is a slow, multi-year process that dictates the millipede’s potential lifespan. Females typically lay hundreds of tiny eggs in the soil, which hatch after a few weeks into juvenile forms. These hatchlings look like miniature adults but begin with only a few pairs of legs and fewer body segments.
Growth occurs through a process called molting, or ecdysis, where the animal sheds its hard outer exoskeleton to increase in size. With each molt, or instar, the juvenile adds new body segments and corresponding pairs of legs, a developmental pattern known as anamorphosis. Because molting is a vulnerable time, millipedes often construct a special chamber in the soil or silk to protect themselves during the process.
Millipedes may undergo seven to ten molts before reaching sexual maturity, a phase that can take one to five years depending on the species. Some species continue to molt periodically even after reaching adulthood, which contributes to their extended lifespan. After molting, the millipede often consumes its discarded exoskeleton to reabsorb valuable nutrients, such as calcium, needed to harden the new cuticle.
Environmental and Species Factors Affecting Longevity
The variation in millipede lifespan is largely due to differences between species and their environments. A direct correlation exists between body size and longevity; smaller species typically have shorter lives than their larger counterparts. The Giant African Millipede, which can grow up to 12 inches long, exemplifies this, frequently living longer than ten years when given proper care in captivity.
Millipedes kept in human care often experience longer and more predictable lifespans compared to their wild counterparts. In the wild, threats like predation, drought, and seasonal food scarcity limit their age. Captivity eliminates these challenges, providing a stable environment with consistent temperature, humidity levels between 70-80%, and an abundant, high-quality food source.
Diet and habitat are directly tied to long-term survival, particularly the need for decaying organic matter and calcium. Access to calcium, often provided through cuttlebone or similar supplements, is paramount for the successful formation of a strong exoskeleton after molting. Without the necessary nutrients and a moist substrate rich in leaf litter, the risk of a fatal molt increases, directly shortening the animal’s life.