Barely bigger around than a quarter, the Northern spider tortoise (Pyxis arachnoides brygooi) hatchling at Cleveland Metroparks Zoo is big news for conservationists working to protect this vulnerable species.

The rare hatching occurred in late March at The RainForest, making the Zoo the first in North America to successfully breed this subspecies of spider tortoise under artificial light only. In the United States, the only other zoo to report hatchings of the species is Knoxville Zoo, which has outdoor pens.

At birth, the Zoo's first spider tortoise hatchling weighed just .385 ounces and measured about 1.3 inches. So far, the hatchling is doing very well in its tank at The RainForest, according to Herpetologist Brad Poynter. It's a very active tortoise, eating small amounts of greens, carrots, potatoes and green beans every day.

The Northern spider tortoise is extremely difficult to breed, and the Zoo has been working at it since 2003. The latest attempt was successful mainly due to the addition of ultraviolet lights over the tank, Poynter said. The Zoo also changed the tortoises' diets to make them more natural -- providing them with mushrooms and flowers similar to those they would eat in their native Madagascar.

The Zoo has five adult Northern spider tortoises. There are only 23 at four zoos nationwide. The Zoo is continuing its efforts to breed its Northern spider tortoises, with another hatching possible within a few months.

Fully grown, Northern spider tortoises measure four to five inches long and weigh less than a pound. From the spiny forests of Madagascar's Southern coast, the species is listed as threatened because its native habitat is being destroyed. Little is known about these tortoises in the wild, but one can spend hours digging a hole in the sand for a nest and laying a tiny egg. At the Zoo, the eggs are held in an incubator for up to seven months before they can hatch.

Northern spider tortoises can live to be more than 100 years old.