Nashville, Tenn. ? A new breeding program at the Memphis Zoo could nearly double the known population of an endangered frog species.

Biologists estimate there are only about 100 adult Mississippi gopher frogs left in the wild, but zoo officials say they’ve successfully produced 94 tadpoles through in-vitro fertilization.

The reclusive, stocky frog measures about three inches long as an adult and has large hind feet made for digging through holes and burrows made by other animals. They have a pointed snout and large eyes, which they cover with their front feet when threatened.

The species once lived in Louisiana’s lower coastal plain, parts of Mississippi and the Mobile River delta in Alabama, but now is only found in two locations in Mississippi.

The zoo, which has been successful at in-vitro fertilization of another amphibian, says this is the first ever captive breeding of the Mississippi gopher frog.