Grow-a-Frog Alert

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African Clawed Frog, Xenopus laevis. Note unwebbed forefeet. Chris Brown/USGS

Nevada Department of Wildlife investigators have begun clamping down on the sale and possession of African Clawed Frogs being sold as mail-order tadpoles by a Florida-based marketing company.

"It's NOT Just an Ordinary Frog!" is the sell line on [Grow-a-Frog], and it turns out the amphibians are, in fact, a potentially invasive species banned in 11 states.

Nevada biologists say they have seized more than 200 of the frogs, mostly after their owners voluntarily reported that they had bought the illegal tadpoles not knowing they were a species considered a threat to local waters.

African Clawed Frogs (Xenopus laevis) grow large, are relatively aggressive for an amphibian and biologists say that they have to potential to establish themselves and become feral predators on native fishes, frogs, birds, and other aquatic life.

In California, invasive populations of this species are blamed for threatening the native Red-legged Frog and Unarmored Three-spined Stickleback, an endangered fish.

One Tough Frog

African Clawed Frogs have already established themselves in a number of U.S. states, in the UK, Germany, and the Netherlands. Although native to sub-Saharan Africa, they can survive temperatures from 0 to 30 degrees C (32 to 86 F) and are reported capable of overwintering under the ice in Wisconsin. They can live through months of drought, buried in mud and can go for up to year without eating.

They are resistant to salt water, are difficult to catch, and have skin toxins that deter many would-predators, including snakes. A single female can produce up to 27,000 eggs in a per clutch and lays multiple batches of eggs each year.

Once used in human pregnancy-testing labs (the female produces eggs when injected with urine from a pregnant woman), African Clawed Frogs continue to be important lab animals. Some early releases into the wild are attributed to lab personnel rather than pet owners.

Still Shipping Frogs

While Grow-a-Frog has paid a fine and agreed to stop shipping the Clawed Frogs to Nevada, it continues to sell its "ORIGINAL Grow-a-Frog Kit" without alerting buyers to the species they are buying.

Grow-a-Frog® Kit.

States that have banned the sale and possession of African Clawed Frogs without a permit include Arizona, California, Hawaii, Kentucky, Louisiana, Nevada, New Jersey, North Carolina, Oregon, Virginia and Washington.

According to an Associated Press story, the Nevada game wardens have been busy with other exotic pets in recent weeks, taking in custody piranhas, a freshwater shark, and a cobra.

"It's not hard to imagine the havoc we could face if these animals escaped and we ended up with a wild population of cobras or piranha in Nevada, Capt. Cameron Waithman, a Nevada Department of Wildlife warden told the AP. "Prohibited species are not only a danger to our ecosystem, they are a danger to our citizens."

Owners of African Clawed Frogs are urged never to release them into the wild. Most responsible pet stores will accept unwanted frogs. Euthanasia can be performed by freezing in a plastic bag for several days and adding bleach or alcohol to the bag before sealing it and disposing of it.

Further Reading:
Columbia University Report * Editor's Choice.

Animal Diversity Profile

Note: African Clawed Frogs (Xenopus laevis) differ from the smaller African Dwarf Frog (Hymenochirus boettgeri) in adult size. Juveniles can be confused, but the Dwarf Frog has webbed fore and hind feet, while Clawed Frog has webbing on its back legs only. African Clawed Frogs reach sizes of up to 5 inches (13 cm).