The common term “thousand legger” refers ambiguously to two different classes of arthropods: millipedes (Class Diplopoda) and centipedes (Class Chilopoda). Despite both belonging to the subphylum Myriapoda, their biological distinctions profoundly influence their feeding habits. Millipedes possess two pairs of legs per body segment, while centipedes have only one pair per segment. This anatomical difference results in distinct ecological roles, making their diets fundamentally different.
The Decomposer Diet of Millipedes
Millipedes are primarily detritivores, acting as nature’s recyclers. Their diet is composed of decaying organic matter, which they consume using small, scraping mouthparts. They mainly feed on dead leaves, rotting wood, and other decomposing plant material, which is critical for nutrient cycling in the soil.
By breaking down this detritus, millipedes help create humus and enrich the soil. They also opportunistically graze on fungi, algae, and sometimes the moist, soft roots of seedlings when decaying matter is scarce. Millipedes are not predators and occasionally consume their own shed exoskeletons to recover valuable nutrients, particularly calcium.
The Predatory Diet of Centipedes
Centipedes, in stark contrast to millipedes, are active, nocturnal predators. Their diet consists of living prey, making them generalist carnivores. They hunt a variety of small invertebrates, including insects, spiders, worms, and even other centipedes.
A distinguishing feature of centipede feeding is the use of venom to subdue their prey. They possess modified front legs called forcipules, located just behind the head, which function as venom-injecting pincers. This potent venom contains neurotoxic peptides that rapidly paralyze or kill their victims. Larger species are known to tackle and consume small vertebrates like lizards, mice, and bats.
Habitat and Food-Seeking Behavior
The dietary differences between the two arthropods are reflected in their food-seeking behaviors and preferred habitats. Millipedes, requiring constant access to moist, decaying matter, move slowly and are often found burrowing beneath leaf litter, rocks, and rotting logs. Their cylindrical bodies and short legs are well-suited for pushing through soil and organic debris while grazing on their food source.
Centipedes are adapted for active hunting, possessing flatter bodies and longer legs that facilitate rapid movement. They seek out similar dark, moist environments like under stones and logs for shelter, but venture out at night to pursue their prey. This need to hunt live food drives them to explore a wider area, sometimes leading them into homes in search of household pests like spiders and silverfish.