Millipedes are terrestrial arthropods and detritivores, commonly found in dark, damp habitats like under leaf litter or within rotting wood. The answer to whether these creatures can survive in water is generally no; they cannot survive full submersion. Millipedes are land-dwelling animals that rely on atmospheric oxygen and lack the biological adaptations necessary for prolonged underwater life.
The Millipede Respiratory System
A millipede’s inability to breathe underwater stems from its specialized respiratory anatomy. Millipedes utilize a tracheal system for gas exchange, a network of air-filled tubes that permeates their body and requires direct access to air.
Oxygen enters this system through small external openings called spiracles, which are positioned along the sides of the body segments. The air travels through finer tracheae, delivering oxygen directly to tissues without relying on a circulatory system. While efficient for land life, this design is vulnerable in water.
When fully submerged, water covers and seals the spiracles. This physical barrier prevents air from entering the tracheal system, stopping gas exchange. Since the millipede cannot extract dissolved oxygen from the water, this blockage quickly leads to suffocation.
Differentiating Moisture Needs from Submersion
Millipedes are frequently associated with damp environments, leading to confusion about their water tolerance. They naturally inhabit moist locations, such as forest soil and compost piles, because they require high environmental humidity to regulate their body water content and prevent desiccation.
Millipedes lose water vapor through their spiracles during respiration because many species lack an effective closing mechanism. Their exoskeleton is not entirely waterproof, further contributing to moisture loss in dry air. Therefore, they must constantly seek damp microclimates to replenish lost water and maintain a healthy internal balance.
The need for a moist habitat is distinct from tolerance for being waterlogged or submerged. A substrate that is too wet can be harmful, as excess water can obstruct the spiracles or increase the risk of fungal infections. Millipedes seek soil that is moist to the touch, not muddy or saturated with standing water.
Accidental Submersion and Survival Limits
Millipedes have limited mobility and generally cannot swim, making accidental submersion a threat. During heavy rains or flooding, their primary survival behavior involves seeking higher ground or burrowing into soil pockets above the water line. If swept into water, their movement is typically ineffective for propulsion.
In complete accidental submersion, a millipede’s survival time is measured in minutes, varying based on water temperature and oxygen concentration. Some species may trap a small air bubble near their spiracles, briefly extending survival, but this is only a temporary measure. The inability to sustain respiration means the millipede will soon deplete any trapped air and drown.
To prevent accidents in captivity, precautions include providing shallow water dishes that contain small stones or pebbles. These objects offer a stable platform, allowing the millipede to drink without the risk of falling into water deep enough to seal its respiratory openings.