Amarinus lacustris
species of crustacean
Amarinus lacustris is a species of freshwater crab from Australia, New Zealand and nearby islands, where it lives in water of various salinities. It grows up to 10 mm (0.4 in) wide, with an H-shaped groove on its back. It is an omnivore and is eaten by crayfish and fish. It was first discovered in Lake Pupuke, near Auckland, and is the only freshwater crab in New Zealand.
Distribution
Amarinus lacustris is widespread in south-eastern Australia, from Tasmania to the Murray-Darling basin in South Australia and Victoria. It reaches as far inland as Lake Colac, Victoria.
In New Zealand, A. lacustris is the only freshwater crab, and is found in a variety of habitats, including lakes, slow-flowing streams and larger rivers. It is found from the lower reaches of the Waikato River to Northland, with a notable population in the Oratia Stream near Auckland.
The species is also found on small islands in the Tasman Sea, such as Lord Howe Island and Norfolk Island, where it was first found at an altitude of "about 3,000 ft" (900 m) on Mount Gower.
Description
Amarinus lacustris grows to a maximum size of 10 millimetres (0.39 in) across the carapace, with a leg span of 20 mm.
The public source identifies “Amarinus lacustris” as species of crustacean. This brief keeps that definition visible, then builds a research path around Amarinus, lacustris and species.
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Jun 26, 2025. The linked authority identifier is Q3933635. None of the 0 selected statements returned an explicit reference.
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This entry incorporates text from “Amarinus lacustris” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.