The Roman Sewer Crab

Dear Blue Lobster:

recently i had the pleasure of rome and there were these cute little freshwater crabs that look like fiddlers that walk around the streets eating garbage and being silly. i asked a native what they were and he said sono greci and spit. what does this mean?

thanks,
phillip

Dear Gentle Sir:

This crab goes by a number of common names. For example, historians know it as the Etruscan Crab or Trajan's Crab while Sicilians call it the Greek Bug. It's generally known as the Roman Crab throughout Italy and Europe in general while local children call it a sewer bug. Its scientific name is Potamon fluviatile, which means little river-goer. Its characteristics are just as interesting as its names.

This crab was imported from Macedonia at Trajan's behest during the Cancercalia, Rome's pagan crab festival. Wishing to impress the populace, he had the crabs hauled into the center of his forum and dumped on open ground. Children ran after the crabs, catching them, while their parents cooked and ate them. Some of the crabs inevitably escaped and lived in the sewers the Etruscans had built centuries before and have thrived there ever since.

Compared to populations in nearby lakes, rivers, and ponds, the sewer crabs are more robust. Just last year, a survey on the crabs revealed that they are, on average, one and one half times the size of non-sewer populations. The reason probably lies in the fact that the omnivorous scavengers have an easier time finding food in the old sewage system. Indeed, a few specimens of this species kept as pets reach the large size of sixty centimeters.