Common Shiny Woodlouse
ExploreAnimal
Common Shiny Woodlouse
oniscus asellus
The Common Shiny Woodlouse (Oniscus asellus) is a remarkably adaptable and widespread terrestrial crustacean. Far from being an insect, this fascinating little creature belongs to the subphylum Crustacea, making it more closely related to ocean-dwelling crabs and lobsters than to beetles or ants. It has adapted exceptionally well to life on land, finding its niche as a vital decomposer in both wild and human-altered environments. By voraciously consuming dead plant material, it plays a crucial role in nutrient cycling, breaking down organic matter and returning essential elements to the soil. Often overlooked as simple garden pests, these woodlice are actually harmless and highly beneficial scavengers. They are incredibly common across Europe and have been introduced to the Americas, where they thrive in moist, dark microhabitats. Observing a Common Shiny Woodlouse provides a direct window into the hidden, microscopic ecosystems of the forest floor and backyard compost heaps, highlighting nature's incredible ability to clean and renew itself. Take the ultimate field guide with you and identify Common Shiny Woodlouse using the Snappit app.
Habitat: Typically found in moist, shaded environments such as under rotting logs, stones, leaf litter, and compost heaps in woodlands, gardens, and urban spaces.
Appearance
The Common Shiny Woodlouse is relatively large and flat, reaching up to 16 millimeters in length. As its name suggests, it is characterized by a glossy, shiny dorsal exoskeleton that typically ranges from dark grey to brown. The shell is often decorated with distinct paler, yellowish mottling, and the edges of its segmented armor form a continuous, light-colored "skirt" around its body. Unlike pillbugs, Oniscus asellus cannot roll itself into a tight defensive ball; instead, it relies on staying flat and clamping down against surfaces. Its head features moderately long, sharply angled antennae with three flagellar segments at the tip, which helps distinguish it from similar species.
KingdomAnimaliaPhylumArthropodaClassMalacostracaOrderIsopodaFamilyOniscidaeGenusOniscus
Category
AnimalRarity
Common
Danger
1/5 · Very low
Snaps
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Interesting facts
Because they breathe using modified, gill-like structures called pleopodal lungs, they must live in damp environments to prevent these 'gills' from drying out.
Unlike the familiar pillbug, the Common Shiny Woodlouse cannot roll up into a ball; if threatened, its main defense is to clamp down incredibly tight against a flat surface.
Woodlice are terrestrial crustaceans, meaning they are more closely related to crabs, shrimp, and lobsters than to insects or centipedes.
Woodlice have copper-based blood utilizing hemocyanin rather than iron-based hemoglobin, which makes their blood appear pale blue when oxygenated.
Special abilities
Ability
Ammonia Gas Excretion
Instead of urinating liquid waste, woodlice conserve water by excreting their nitrogenous waste as ammonia gas directly through their exoskeleton.
Ability
Heavy Metal Tolerance
They can accumulate and tolerate high levels of heavy metals like copper and zinc in their hepatopancreas, allowing them to survive in heavily polluted environments.
Ability
Brood Pouch Rearing
Females develop a fluid-filled marsupium (brood pouch) on their underside where they carry and protect their eggs and newly hatched young until they are ready to emerge.
Measurements & details
- Length
- 1 cm
- Weight
- 0.00005-0.00015 kg
- Lifespan
- 2-4 years
- Clutch Size
- 20-60
- Incubation
- 30-45 days
Diet & Feeding
They primarily consume dead and decaying plant matter, playing a critical role in nutrient cycling and soil health.
Age differences: Newly hatched young, called mancas, consume the same decaying matter but often eat their mother's feces to establish the necessary gut microbiome to digest woody material.
Primary Foods
- Decaying leaves
- Rotting wood
- Fungi
- Fallen fruit
Foraging Method
- Foraging
Ecological connections
eaten by
Woodlouse Spider
Dysdera crocata
Preyed upon specifically by specialized spiders with large fangs designed to pierce their tough exoskeleton.
eaten by
Common Toad
Bufo bufo
Consumed by small amphibians foraging in the leaf litter during the night.
eaten by
Common Shrew
Sorex araneus
Eaten by small, highly active insectivorous mammals scurrying across the forest floor.
Traits
No trait badges are assigned for this object yet.
Also known as
No aliases listed yet.
Collections
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Safety
Danger
1/5 · Very low
No special safety notes yet.
Frequently Asked Questions
How to identify Common Shiny Woodlouse?
The easiest way to identify Common Shiny Woodlouse is to use the Snappit nature identifier app.
How long is Common Shiny Woodlouse?
1 cm
How much does Common Shiny Woodlouse weigh?
0.00005-0.00015 kg
How long does Common Shiny Woodlouse live?
2-4 years
What does Common Shiny Woodlouse eat?
They primarily consume dead and decaying plant matter, playing a critical role in nutrient cycling and soil health.
Where is Common Shiny Woodlouse usually found?
Typically found in moist, shaded environments such as under rotting logs, stones, leaf litter, and compost heaps in woodlands, gardens, and urban spaces.
How does Common Shiny Woodlouse hunt?
Foraging
How many eggs does Common Shiny Woodlouse lay?
20-60
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