The dark-bellied marshotter, also known as the Eurasian otter, is a semi-aquatic mammal found in Europe and Asia. Synonyms for this species include the European otter, common otter, river otter, and water dog. These creatures have a sleek, waterproof coat that can range in color from light brown to almost black, and they are skilled swimmers and hunters. Marshotters feed on fish, crustaceans, and other small aquatic animals. Unfortunately, due to habitat loss and pollution, many populations of marshotters are under threat. Conservation efforts are underway to protect and preserve these important aquatic predators.