Indigenous to southern and sub-Sahara Africa, the African clawed frog (Xenopus laevis) is a predatory aquatic species known for its adaptability to a diverse range of environmental conditions. African clawed frogs inhabit warm, stagnant bodies of water and are often found in areas with temperatures of 60 to 80 degrees Fahrenheit. These frogs only leave their aquatic habitat to migrate to other bodies of water, sometimes lying dormant in mud for up to one year amidst their pond drying up.
How to Identify: African clawed frogs have smooth, mottled grey to brown colored skin with an ivory to yellow underside. To protect itself against predators, they can change their color, camouflaging into their surroundings. These frogs are about 5 inches long, not including its legs, and have a flattened build. African clawed frogs have small front limbs with non-webbed, cornified fingertips and large, webbed hind legs. Instead of hopping, African clawed frogs move in a crawling motion. Their eyes and nostrils sit atop their wedge-shaped head, with their eyes protected by a transparent covering. Unique for their lack of a tongue, teeth and visible ears, they sense movements and vibrations in water through lateral lines running down the length of their body and underside.
Spread: African clawed frogs are an invasive species on four continents, including North America. Currently, they occupy two Washington State watersheds. In 2015, locals discovered the African clawed frog in a stormwater pond in Lacey, causing concern. Then in August 2020, they were spotted along Tibbets Creek in Issaquah. Experts suspect that both introductions were either escapes or intentional releases from private aquariums. Once in the wild, African clawed frogs rapidly reproduce, doubling their range and population within 10 years.
Impact: African clawed frogs can have a devastating impact on native ecosystems. They begin life as filter feeders, becoming scavengers as they mature. Once adult frogs enter a new area, native species, especially amphibians are at risk. African clawed frogs are non-selective predators that consume arthropods and organic waste such as water insects, small fish, tadpoles, worms, aquatic insect larvae, crustaceans, and freshwater snails. This causes extreme harm to ecosystems, as African clawed frogs predate on and compete with native species leading to their demise.
African clawed frogs also carry the amphibian fungus Batrachochytrium dendrobatidis (Bd, a type of chytrid fungus) and ranavirus disease. Chytrid fungus, Bd, kills amphibians by causing their skin to become thick, making it difficult for species to breathe, drink water, and absorb important electrolytes through their skin. Ranavirus has also led to declines in frogs, reptiles, and fish populations around the world, causing severe and often deadly infections amongst cold-blooded animals.
Prevention: There are several ways to prevent African clawed frogs from invading native environments. To start, those in possession of the species should never release them into the wild. Programs such as WDFW’s Don’t Let Loose aim to help owners rehome unwanted pets by educating and providing resources for relocation. There are also many ways to report invasive species sitings including the Washington Invasive Species Council Report a Siting page, the Oregon Invasive Species Online Hotline, and the Montana Invasive Species Report webpage and hotline. Raising awareness about African clawed frogs and their effect on the environment is critical to further protect native species and Washington’s waters.