Carr Slater

🔤 Taxonomy

Ligidium hypnorum (Cuvier, 1792) is accepted. Older combinations include Oniscus hypnorum, O. agilis and Ligia melanocephala. Its antennal flagellum has numerous bead-like segments, unlike the three long segments of the superficially similar Philoscia muscorum.

📌 Description

The carr slater is a glossy, mottled, long-legged woodlouse that rarely exceeds 9 mm. It runs extremely quickly and cannot roll into a ball. Its dependence on waterlogged litter, fen carr and wet woodland makes it a specialist culture rather than a general bioactive clean-up crew.

Care point	Practical target
Adult length	about 0.6–0.9 cm
Starter colony	25 × 20 × 15 cm or larger
Temperature	12–20 °C
Substrate	9–11 cm, almost entirely wet but oxygenated
Staple	mature deciduous and sedge litter, rotten wood
Main risk	brief drying, heat or stagnant anaerobic substrate

🌍 Distribution

The species occurs across Europe and western Asia, from southern England, Denmark and the southern Baltic east to the Black Sea region and Iran. It is absent from the Mediterranean basin and from Ireland. The map uses a conservative European core; broad country shading cannot show its scattered dependence on wetlands and humid woodland.

Regional climate averages are omitted because a waterlogged moss or litter pocket remains far cooler and wetter than the surrounding weather station. That buffered refuge, not a national climate, determines care.

Conservative native-range map

⚖️ Legal status

Checked on 2026-08-29: L. hypnorum was not found in CITES, EU wildlife-trade Annexes A–D under Regulation (EU) 2026/1383, or Bern Appendices II–III.

Local and national rules can still protect wetlands, ancient woodland, reserves and their invertebrates, and may regulate collection, soil transport, sale or import. Obtain permission, prefer documented captive stock, retain locality records and never release a culture.

🤌 Husbandry

This is not a beginner isopod. Start 20–30 verified animals in a sealed-edge 25 × 20 × 15 cm enclosure with very fine screened vents. Provide 9–11 cm of mature soil, leaf mould and rotten wood. Keep nearly the whole lower layer wet, but maintain cross-ventilation and loose structure so it remains oxygenated.

Quarantine for 60 days with separate tools and confirm adults under magnification. ReptiFiles has no species guide and there is little species-level captive work; temperatures and enclosure targets are cautious values derived from its cool wet field habitat, not experimentally proven optima.

💡 Lighting

UVB is unnecessary. Provide 8–14 hours of dim diffuse light and permanent shade under wood, moss and tussocks. Direct sun and warm lamps are dangerous.

🌡 Heating and temperature

Maintain 12–20 °C, with an 8–15 °C refuge and nights around 7–15 °C. Avoid prolonged temperatures above 22–23 °C. Seasonal room cooling may reduce activity, but do not freeze the substrate or force winter cycling on a weak culture.

No basking heat is needed. Cooling the room is safer than flooding an overheated enclosure.

💧 Humidity and water

Use 85–100% RH only as a rough indicator. Moss, dead wood and lower leaf litter should remain wet to the touch, while their pore spaces still contain air. Add water slowly into one corner and monitor the bottom through a clear wall.

Do not add a pool or open dish: this terrestrial species needs saturated refuges, not swimming water. A sewage-like odour or black substrate signals anaerobic conditions; sudden surface crowding often precedes drying or oxygen loss.

🌿 Enclosure and decoration

Use pesticide-free loam or clay-rich woodland soil, mature leaf mould, peat-free organic matter and soft rotten hardwood. Cover with deciduous leaves, sedge litter, moss, bark flats and small grass tussocks. Build loose layers rather than compressing mud.

Offer cuttlebone or fine limestone even though natural sites may include acidic peat. Avoid pure coir, fertilizer, resinous wood and heavy stones that squeeze water and air from the substrate.

🪳 Feeding

Keep mature deciduous, reed or sedge litter and rotten wood continuously available. Add minute mushroom, squash or carrot portions every three to five days and a very small protein feed every 7–10 days.

Remove fresh remnants within 24 hours. Appetite may be low during cool periods; uneaten rich food should not be replaced with a larger portion.

🥚 Breeding

Females retain embryos in a marsupium and release mancae, represented as viviparous in metadata. Published ecology confirms reproduction has been studied, but dependable species-specific captive maturation and brood targets are not available.

Preserve cool saturated pores and mature microbial food. Do not isolate gravid females or disturb the substrate searching for young. Divide only a strong mixed-age colony and transfer wet wood, litter and mature soil together.

🩺 Common problems

Rapid desiccation: restore deep moisture immediately and reduce excessive ventilation area.
Heat-related losses: move the enclosure to a cooler room; do not flood warm substrate.
Anaerobic soil: replace only the foul portion and rebuild loose wet layers with airflow.
Escapes: use very fine mesh and open the container over a tray.
Wrong identity: examine antennal segmentation and retain locality data.
Few young: reduce disturbance and stabilize cool moisture and mature food.

📌 Conclusion

Ligidium hypnorum is for keepers able to hold a cool, almost saturated but aerated forest-floor system. Its narrow moisture margin and speed make ordinary tropical or partly dry isopod setups unsuitable.