What is "black slug"

n. An omnivorous slug found in Europe and the Pacific Northwest, (taxlink Arion ater species noshow=1). It is not always black, despite the name.

The black slug (also known as black arion, European black slug, or large black slug) Arion ater L. is a large terrestrial gastropod mollusk in the family Arionidae—the round back slugs. Land slugs lack shells like other terrestrial mollusks (such as snails). Without such shells, slugs produce unappetizing mucus—that may also contain toxins—to deter predators. Additionally, terrestrial slugs produce two other forms of mucus that facilitate locomotion and prevent death from drying. Such mollusks are hermaphroditic preferring to find mates. Slugs most often function as decomposers but are also often omnivores. Arion ater is one such slug, decomposing organic matter, preying on other organisms, and consuming vegetative matter—including agricultural crops. Native to Europe, the black slug is an invasive species in Australia, Canada (British Columbia, Newfoundland, Quebec), and the United States—Pacific Northwest.