The Signal Crayfish, scientifically known as *Pacifastacus leniusculus*, is a freshwater crustacean native to North America. It is recognized by its distinctive blue-green color and the bright red coloration on its claws, which resemble signals. These crayfish typically inhabit rivers, lakes, and streams, where they play a crucial role in the ecosystem by helping to recycle nutrients. Introduced to various regions, including parts of Europe and Asia, the Signal Crayfish has become an invasive species, often outcompeting local crayfish populations. They are omnivorous, feeding on plants, insects, and detritus, which can impact the local food web and aquatic habitats.