freshwater crab found near wooded streams rivers lakes broad ecological adults typically reach size year lifespan inhabit aggressive apparently native harvested food classical antiquity threatened island populations particularly vulnerable subspecies conservation icon population rome brought founding description reach length millimetres females generally smaller males crabs body roughly square reduced abdomen beneath bears pairs legs armed large claws life span typically years occur winter mating lasts min hours spawning usually taking place august females carry eggs abdomen hatch directly juvenile crabs having passed stages inside egg edible indicated alternative specific epithet known ancient greeks probably species depicted medals found recently species depicted coin series coins introduction euro ecology diet feeding vegetable debris algae surfaces frogs invertebrates insect larvae worms predator number animals including rats birds prey significant predator mankind individual able catch season adults occupy smaller individuals shelter stones entrances stream edge water level long probably serve protect crabs extreme cold aggressive species attacking larger right individuals right handed found south watershed contrast occurs sides mountains ranges overlap species inhabit water courses apparently crab forced live favourable locations crab survive non indigenous pose greater threat native greatest threats remain pollution draining wetlands distribution natural range highly fragmented covers parts countries mediterranean coastline found mainland italy greece found number islands including sicily malta species widespread declining numbers populations particularly vulnerable italy widely distributed mainland italy especially provinces island sicily found far north longer occurs north population discovered ruins heart rome living canals built connect based genetic analysis demonstrated crabs similar greece researchers believe brought greeks founding city years ago crabs unusual size longevity years interpreted evidence long established population analogy island malta island malta rare restricted locations west island single population inhabits stretch river metres long balkans known occur croatia montenegro albania greece species balkans replaced northeastern greece mainland greece found rivers known occur site found single site taxonomy western limit genus species genus occur eastern_europe middle_east far east northwestern india populations represent separate cryptic species population described divided subspecies live north_africa later combined separated species nominate subspecies equivalent current species divided tribes found northern italy southern italy found parts greece geographical distribution reported suggested tribe inhabited greek island despite wealth taxa rarely scientists questioned directly value defining taxa population malta described separate subspecies taxon conservation icon malta following legal protection scientists recognise taxon
Potamon fluviatile