Spotting an Acaeroplastes melanurus is a treat for any macro-enthusiast exploring the sun-drenched Mediterranean. This charming terrestrial isopod is a master of the rocky coastline.
Identification
Measuring a modest 5–8 mm, this woodlouse is easily recognized by its striking "black tail"—the feature that gives it its name (*melanurus*). While the main body is an elegant mottled grey or warm brown, the terminal segments (the telson and uropods) are deeply pigmented, appearing almost charcoal-black. Look closely at the margins of its body segments; you’ll often see a row of pale yellow or orange spots that glow against the darker background. Unlike the common *Porcellio scaber*, *A. melanurus* has a more polished, slightly translucent appearance and a distinctively rounded, "neat" silhouette.
Habitat & Range
This species is a Mediterranean specialist, found primarily along the coasts of Southern Europe and North Africa. It thrives in the "macchia" (shrubland) and among limestone crevices. You won’t find it in the deep, damp woods; instead, it prefers the edges of paths and rocky outcrops where the air is salty and the soil is well-drained.
Behaviour
While many woodlice are sluggish, *A. melanurus* is a surprisingly nimble "runner." If you flip a stone, don’t expect it to roll into a ball (it cannot conglobate); instead, it will scuttle with impressive speed toward the nearest shadow. They are social creatures, often found huddling in "micro-colonies" to conserve moisture during the heat of the day, becoming most active during the humid twilight hours.
Diet
As a vital detritivore, it spends its nights grazing on the tough, leathery leaf litter of Mediterranean plants like Holm Oak and Myrtle. It also feeds on lichen and microscopic fungi growing on sun-baked limestone, acting as a tiny, efficient recycler of the scrubland.
Fascinating Fact
Despite living in dry, rocky environments, *Acaeroplastes melanurus* breathes through "lungs" located on its back legs! These specialized structures, called pseudotracheae, allow it to extract oxygen from the air while minimizing water loss, a brilliant evolutionary hack for a crustacean living on dry land.