Nestled in the heart of Rome, the ancient ruins of the Mercati di Traiano – a bustling trading and administrative complex built around 110 AD – are still occupied to this day, but by something rather less imposing than a noisy throng of sword-clad Romans.
Hidden among the site’s underground waterways is an extensive population of freshwater crabs, a species now endangered in its range across southern Europe.
The colony wasn’t discovered until the 1980s, so nobody knows for sure how long the crustaceans have been here, but it’s likely hundreds of years. And it seems they’re faring pretty well.
- "Uncharted territory": soft tissue of ancient animal found entombed in volcanic rock near Rome
- How did the Romans capture lions and tigers for bloodthirsty entertainment at the Colosseum?
“Scientists studying the population have realised that these urban individuals grow much larger than their counterparts elsewhere, with a body size of 7cm, compared to an average of 5cm,” says Emanuele. “It seems to be a case of isolated population gigantism, a phenomenon seen on islands, where a lack of predators and abundance of hiding places allow for extra growth.”
- “A colossal crab the size of a car tyre was pushing against my door”
- What's the difference between a lobster and a crab? We explain what makes a crab a crab - and a lobster a lobster
Crustacean comforts For the crabs, life in these empty halls is certainly very comfortable. There’s a regular, well-stocked buffet of dead rodents, cockroaches, bird droppings, plants and discarded food. And, because special permission is required to enter the site, disturbance from humans is minimal.
The crustaceans while their days away in the cool of the underground, generally emerging at night or during rainy days. “On this particular spring morning, I saw just one or two crabs walking around, and a few more under stones in the damp grass,” says Emanuele. “Watching the strength-display of this individual was like watching the last gladiator of Rome.
It shows how resilient wildlife can be, if we leave even a little space for it.”
- Drunken feasts, role reversals and sacrifice: Before Christmas there was this Roman party in December – and it was absolutely out of control
- Did the Romans bring lions to England to maul criminals and prisoners of war to death for gruesome entertainment?
Photo and words by Emanuele Biggi
