page_title: Hemilepistus reaumuri
section_title: Ecology
hierarchical_section_title: Hemilepistus reaumuri / Ecology
caption_attribution_description: עברית: עביד צהוב English: Scorpio maurus palmatus , Israel.
context_page_description: Hemilepistus reaumuri is a species of woodlouse that lives in and around the deserts of North Africa and the Middle East, "the driest habitat conquered by any species of crustacean". It reaches a length of 22 mm and a width of up to 12 mm, and has seven pairs of legs which hold its body unusually high off the ground. The species was described in the Description de l'Égypte after the French Campaign in Egypt and Syria of 1798–1801, but was first formally named by Henri Milne-Edwards in 1840 as Porcellio reaumuri. It reached its current scientific name in 1930 after the former subgenus Hemilepistus was raised to the rank of genus.
  H. reaumuri occurs at great population densities and fills an important niche in the desert ecosystem. It feeds on plant leaves, obtains most of its water from moisture in the air and sand, and is in turn an important prey item for the scorpion Scorpio maurus. H. reaumuri is only able to survive in such arid conditions because it has developed parental care of its offspring. Adults dig burrows which are inhabited by family groups, which are recognised using pheromones.
context_section_description: Hemilepistus reaumuri is an important part of the desert ecosystem. It has been found at population densities of up to 480,000 individuals per hectare, which is equivalent to a biomass of 19.2 kg/ha; in comparison, desert mammals are estimated to have a combined biomass of 39.9 kg/ha. The main predator of H. reaumuri is the scorpion Scorpio maurus, and it may compose up to 70% of the scorpion's diet. It appears to be vulnerable to attack only on the surface; no predators are known to attack H. reaumuri in its burrows.
  Hemilepistus reaumuri can only escape the heat of the desert by constructing a burrow, which is time-consuming and energetically costly. One parent must therefore guard the burrow while the other forages for food. H. reaumuri can spend up to ten months of the year returning to the surface to forage, which is far longer than species which do not dig burrows, such as Armadillidium vulgare or Armadillo officinalis. Although they will forage at temperatures as high as 35 °C (95 °F), these woodlice retreat to their burrow when the temperature is too high. They are also unable to tolerate air with a relative humidity below 6%, which often occurs at depths of up to 30 centimetres (12 in) in the desert soil in the hottest months, and the burrows are therefore dug at least 40–50 cm (16–20 in) deep. The burrows are vertical, with a single entrance 9–12 mm (0.35–0.47 in) in diameter, and there may be up to 20 burrows per square metre (nearly 2 per square foot) in favourable areas. If a foraging woodlouse cannot find the burrow entrance on its return, it employs a complex and efficient strategy to find it again. It begins with a spirally widening search, and develops into a more meandering approach the longer it is unable to find the burrow.
  Hemilepistus reaumuri has a significantly higher biomass than other herbivores in the Negev Desert, making it an important part of herbivore–omnivore food chains. They spend the day provisioning their burrows with leaf material from the surface of the desert, sometimes resting under stones or in crevices of rocks. Their faeces accumulates on the surface, and forms a "faecal embankment", similar to a levee, which demarcates the extent of the home territory of the colony in the burrow. The plants Artemisia herba-alba and Haloxylon scoparium are the most abundant bushes in the Negev desert, and seem to make up most of the diet of H. reaumuri.
  The bulk of the water intake of Hemilepistus reaumuri is by taking up water vapour from saturated air and by eating damp sand. Water loss is minimised by the rectal epithelium, which absorbs water, ensuring that the faeces is drier than the food the animal consumed. Evaporation of water through the permeable exoskeleton may, however, provide a valuable cooling effect.
caption: Scorpio maurus is a major predator of Hemilepistus reaumuri.
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