Asellus aquaticus

Asellus aquaticus is a freshwater crustacean resembling a woodlouse. It is known by various common names including pond slater, water louse, aquatic sowbug, water hoglouse and cress bug.

Asellus aquaticus
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Malacostraca
Order:	Isopoda
Family:	Asellidae
Genus:	Asellus
Species:	A. aquaticus
Binomial name
Asellus aquaticus (Linnaeus, 1758)

Ecology

Asellus aquaticus is common throughout the temperate zone, including Europe and Russia.^[1] It is found in rivers, streams and standing water, particularly where there are plenty of stones under which it hides, but it is not found where the water is strongly acidic.^[2] It is a detritivore.

Asellus aquaticus is relatively tolerant of a range of pollutants and has been used as an indicator of water quality.^[1]

Life cycle and reproduction

Asellus aquaticus can breed throughout the year, if the temperature is high enough: they do not breed under cold temperatures. Maturity can be reached in few months under warm summer temperatures, but maturation may take as much as two years in permanently cold water bodies (e.g., high-latitude or mountain waters).^[3] Life span varies similarly: from 9 months in South Africa to 20 months in Northern Europe. Females carry eggs in brood pouches underneath their body.^[4]

Aquarium keeping

Aquarists worldwide are showing increasing interest towards A. aquaticus as a low-maintenance freshwater aquarium pet and tank cleaner. While often sold as live food for other fish, some keepers in the US and Germany have started selectively breeding A. aquaticus to be sold as pets, usually from online platforms like eBay.^[5]

Conservation

• Crustaceans portal
• Arthropods portal

A number of subspecies are considered to be endangered including:

• Asellus aquaticus carniolicus, endemic to Slovenia.^[6]
• Asellus aquaticus cavernicolus found only in Italy and Slovenia.^[7]
• Asellus aquaticus cyclobranchialis, endemic to Slovenia.^[8]

References

1. Lorraine Maltby (1991). "Pollution as a probe of life-history adaptation in Asellus aquaticus (Isopoda)". Oikos. 61 (1): 11–18. doi:10.2307/3545402. JSTOR 3545402.
2. Brian A. Whitton (1982). Rivers, Lakes and Marshes. London: Hodder & Stoughton. p. 131. ISBN 0-340-23155-6.
3. Karen Anna Økland (1978). "Life history and growth of Asellus aquaticus (L.) in relation to environment in a eutrophic lake in Norway". Hydrobiologia. 59 (3): 243–259. doi:10.1007/BF00036504. S2CID 21349016.
4. P. Sterry (1997). Complete British Wildlife. Collins. p. 212. ISBN 0-583-33638-8.
5. "List of online distributors of freshwater isopods worldwide". Shrimp Keep. Archived from the original on 17 February 2022. Retrieved 22 May 2020.
6. Sket, B. (1996). "Asellus aquaticus ssp. carniolicus". IUCN Red List of Threatened Species. 1996: e.T2157A9301503. doi:10.2305/IUCN.UK.1996.RLTS.T2157A9301503.en. Retrieved 13 November 2021.
7. Sket, B. (1996). "Asellus aquaticus ssp. cavernicolus". IUCN Red List of Threatened Species. 1996: e.T2158A9302045. doi:10.2305/IUCN.UK.1996.RLTS.T2158A9302045.en. Retrieved 13 November 2021.
8. Sket, B. (1996). "Asellus aquaticus ssp. cyclobranchialis". IUCN Red List of Threatened Species. 1996: e.T2159A9302079. doi:10.2305/IUCN.UK.1996.RLTS.T2159A9302079.en. Retrieved 13 November 2021.