Clam fishermen in the Sacca di Goro, a lagoon in the delta of the Po River, pay a steep price for the blue crab's voracity. It eats anything, with a preference for the clams upon which the region's economy is based. It is also not averse to shrimp, small fish, and other crab species that inhabit the lagoons of the upper Adriatic Sea. Before two or three years ago, finding a blue crab in nets and pots was a curious occurrence, but now it's a major problem: the blue crab has invaded the lagoons and there appears to be no way to stop it. The blue crab is the common name for Callinectes sapidus, a species native to the east coast of the United States that is widespread from southern Canada to northern Argentina. Multiple studies have estimated that it arrived in the Mediterranean Sea around the middle of the twentieth century, first in Tunisia and Algeria, then the Aegean Sea and Turkey, and finally the Adriatic Sea. One of the most widely accepted hypotheses is that he traveled from North America to Europe in the ballast waters of merchant ships. So, it's a non-native species that humans have relocated to a new area, either deliberately or accidentally altering the natural habitat of the species in the process. The width of its carapace can reach and in some cases exceed 23 centimeters in males and 20 centimeters in females. Approximately 9 centimeters in length. It attacks its prey with two triangular frontal and nine long, pointed lateral denticles. It is known as the blue crab due to its large, blue-colored claws that can damage fishing nets. In the United States, particularly in the Chesapeake Bay between Maryland and Virginia, this item is regarded as a crucial component of the fishing industry. It is caught, steamed or boiled, and incorporated into pastas, salads, and soups. They are not simple recipes, as the pulp requires at least twenty minutes of preparation time. It can cost more than $100 per kilogram, or just over 90 euros. Even in Italy, some restaurants have begun to include it on their menus: a few years ago, when it was unknown, it was sold for three or four euros per kilogram, but now it can cost up to ten euros.