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A
closer look at Potamon fluviatile, the crab who left the sea
to live on land
By
Francesco Tomasinelli
UPDATED
01/08/2006
UPDATED 01/08/2006
These Crustaceans are opportunists
and can feed on a wide variety of preys in the water and even deep in
the woods, where they venture at night or in rainy days. They emerge
at night from their hides to hunt small creatures, like tadpoles and
insects fallen into the waters. If the opportunity arises crabs are
even able to capture small frogs and fishes.
Bad attitude, nocturnal habits and the size of a hand makes Potamon
a difficult target for many predators. But the crabs are pretty vulnerable
to pollution and habitat degradation, even if in the last years a population
of these crustaceans was surprisingly found in good health even in the
city of Rome, in an unpolluted area. Young crabs are more tied to water
than adults. Females mate in late spring and give birth to young’s
in summer. They pass the first months in the water (without any stage
in the sea, as happens with most tropical forest crabs), before venturing
around in the woods.
Other species of crustaceans
live in freshwater habitats in Europe even if they have slightly different
preferences: the shy European crayfish Austropotamobius and
the aggressive and bigger Louisiana crayfish Procambarus clarkii,
an invading species from United States. A series of experiments involving
fights between different species (Potamom, Austrapotamobius, Procambarus)
were recently carried on by the University of Florence to better understand
the balance of power in European streams. The crab, with great surprise
of everybody, proved superior to crayfishes of similar size, including
the fearsome american invader.
Many thanks to Sara Fratini, Silvia Barbaresi, Alessio Bruni, Lorenzo
Gori, Laura Calevo and Stefano Cannicci for precious informations and
help.
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