northern white rhino dies

A northern white rhino has died at a San Diego zoo, leaving only five worldwide and bringing the species closer to extinction.

Angalifu, 44, died of old age Sunday at the San Diego Zoo Safari Park.

San Diego Zoo Safari Park announced that Angalifu, one of six remaining northern white rhinos in the world, died Sunday. Credit: San Diego Zoo/Helene Hoffman

"With Angalifu's passing, only five northern white rhinos are left on the planet, including Nola, our elderly female," the zoo said in a statement.

Of the handful of northern white rhinos left worldwide, a few are at a wildlife conservancy in Kenya. There are no known northern white rhinos left in the wild.

Northern white rhinos and southern white rhinos are different subspecies genetically.

Last year, the International Union for Conservation of Nature declared the northern white rhino as "teetering on the brink of extinction."

Rhinos are killed by poachers almost exclusively for their horns, which sell for tens of thousands of dollars.

Experts say that rhino horn is becoming more lucrative than drugs. The demand is driven primarily by buyers in East Asia, who believe it cures a series of ailments.

Organized crime syndicates are using military-grade helicopters, night-vision equipment and guns fitted with silencers, taking rhino poaching to a whole new level and leaving conservationists struggling to keep up.