Batrachochytrium dendrobatidis is a pathogenic fungus that primarily affects amphibians, particularly frogs. It causes a disease known as chytridiomycosis, which disrupts the skin's ability to regulate water and electrolytes, leading to severe health issues and often death in infected animals. This fungus has been linked to significant declines in amphibian populations worldwide, contributing to the extinction of several species. It thrives in moist environments and can spread rapidly, making it a major concern for biodiversity and conservation efforts aimed at protecting vulnerable amphibian species.