Rolly pollies, also known as pill bugs or woodlice, are common in gardens and other damp environments. Often mistaken for insects, they are actually terrestrial crustaceans, more closely related to marine animals like shrimp, crabs, and lobsters. Their distinctive ability to curl into a tight ball when disturbed, a defense mechanism called conglobation, gives them their familiar “roly poly” nickname.
What Rolly Pollies Eat
Rolly pollies are detritivores, primarily eating decaying organic matter. They break down dead plant material like rotting leaves, wood, and other vegetative debris found in moist habitats. Fungi and mosses also form part of their diet, contributing to decomposition.
While preferring decaying matter, rolly pollies may occasionally feed on soft, healthy plant parts, especially seedlings or fruits in contact with the soil. This behavior is more common during wet conditions or when preferred food sources are scarce. They also consume animal feces, including their own, and sometimes carrion or shed animal skin. This practice, known as coprophagy, helps them re-ingest nutrients.
How Rolly Pollies Hydrate
Rolly pollies do not drink water conventionally. Instead, they absorb moisture directly from their surroundings, primarily through their bodies and damp food. Their survival depends on a moist environment because they breathe through gill-like structures. These gills, similar to those of their aquatic relatives, require constant moisture to function and extract oxygen from the air.
Prolonged exposure to dry conditions can cause their gills to dry out, leading to suffocation. They actively seek damp, dark places like under rocks, logs, or leaf litter to prevent desiccation. While needing humidity, they cannot survive being submerged in water for extended periods and can drown. Their ability to roll into a ball also helps them conserve moisture by reducing the surface area exposed to dry air.
Their Ecological Contribution
Rolly pollies serve as decomposers within ecosystems. By consuming decaying organic material, they break it down into smaller pieces, speeding up decomposition. This returns valuable nutrients to the soil, contributing to soil health and fertility. Their presence helps enrich the soil, supporting plant growth.
These crustaceans also remove heavy metals from the soil. They ingest and crystallize heavy metals like lead, cadmium, arsenic, copper, and zinc within their guts. This process prevents these toxins from leaching into groundwater, allowing rolly pollies to thrive in contaminated areas where other species might not survive. They contribute to a healthy soil food web, and their activity can help aerate the soil.