These giant freshwater crabs could be your new Roman Empire.
In 2005, archaeologists studying the Forum of Trajan, a historic Roman ruin site, discovered an ancient species of crab, Potamon fluvial. The only freshwater crab species native to Italy. Researchers suspect that the crab has been in the region since ancient times, long before people knew the region was known for its gelato and pasta.
“The subsurface of Rome, especially in the area of the ancient Roman Forum, is very rich in water, with many corridors and shelters for survival,” Marco Seminara, an environmental biologist at Sapienza University of Rome, told National Geographic.
“It doesn’t surprise me that these animals have lived there for so long.”
With the collapse of the Roman Empire, the crabs adopted a low profile so they could safely maneuver through the city’s underground sewer systems, surfacing only at night to feed on animal remains and other organic matter.
Nature photographer Emanule Biggi has described the crabs as a ‘Wall-E of nature’. He is writing:
“Its fierce temperament protects it from disturbance by many predators such as water snakes and smaller birds, and even from non-native species such as the Louisiana freshwater crayfish.”
However, today data indicate that the species may be endangered.
While researchers caught and identified about 500 crabs during the peak of their research, between 2004 and 2006, rising temperatures have made them nearly impossible to find.
Despite their large size (scientists say Rome crabs were between 13 and 20% larger than other members of the same species) they have managed to tunnel further into their hidden channels to stay cool, because the surface of their home is hotter and becomes less warm. damp.
Human excavations are also responsible for their dwindling population, uncovering a network of underground canals that once protected the crabs. Now predators such as seagulls and crows have breached the crabs’ habitats.
Seminara told National Geographic that he finds more crab body parts than live crabs these days. The species is also on the IUCN Red List of Endangered Species as “Near Threatened”.
To save this species – which has existed for centuries – experts say they need money to study it.
In 2020, the Colosseum recruited naturalists to help study and monitor several species living in the area between the Colosseum and the Roman Forum. Seminara accompanied naturalist Gianluca Damiani on this mission, but the results were far less exciting than the original discovery of the species.
In the past three years, only six new crabs have been identified, Damiani told National Geographic.
“Now they’ve gone even deeper,” Damiani said. “They’re impossible to find.”
Although scientists do not conclude that the crabs are currently in danger of extinction, they can conclude that the crab population is rapidly declining.
“We would like to study these animals because they deserve not only to be studied, but to be saved,” Damiani said. “This population cannot disappear.”
Damiani and his colleagues have asked for permission to install grilles and signs informing people about the crabs, though the city has denied those requests.
Seminara attributes this to Rome’s desire to keep the area unchanged for tourists, but Seminara argues that the interest in these crabs is an attraction in itself.
“Their existence is definitely folkloric. It would be like finding a crab living in Central Park,” he explained to National Geographic. “This is a unique animal.”
“The fact that the Roman Forum contains the only large freshwater crustacean animal we have in Italian waters has and will always arouse a certain astonishment.”
For now, the crab species – which also lives in other Mediterranean areas such as Malta and the Balkan Peninsula – is protected by local and national laws. But experts believe environmental education and communication are crucial in saving the crabs.
For Damiani, it starts with sharing their story.
“A stone’s throw from the Colosseum, in the heart of Rome, extraordinary crustaceans survive,” he writes in an Instagram caption, showing his images of the crabs in their natural habitat.
“The last survivors are hiding among sewers and canals,” he continues, “descending deeper and deeper into an urban jungle that is rapidly changing.”
Header image courtesy of Amphipolis (CC BY-SA 2.0)