(CNN)Lonely George has died.
With him went an entire species.
Formally known as Achatinella apexfulva, the 14-year-old Hawaiian tree snail was the last of its kind on the planet.
He had been lonely since shortly after his birth, living in a captive breeding facility at the University of Hawaii as part of a final attempt to save his species and others from extinction.
The Achatinella apexfulva now joins hundreds of snail species that have vanished from the Hawaiian islands over the last several decades, University of Hawaii Professor Emeritus Michael Hadfield said.
"The number of species in Hawaii was somewhere approaching 800 in 11 different families," he said. Three-fourths of those species, he said, are now extinct.
"They were the best known tree snails, big and pretty snails, once hyper abundant in the forest ... of the island," Hadfield said of the Achatinella genus -- which included Lonely George. "There's no doubt that only 10 or so of those (species) still exist, and none of them will survive in the next 10 years."
"The extinctions have just been horrendous."
Hadfield ran a conservation lab for a large group of snails in the family to which Lonely George belonged. The lab studied the snails' population growth and, in 1997, collected the last ten known snails in George's species. Most of them later died, leaving only George.
The Department of Land and Natural Resources called George's death "a significant loss to locals as he was featured in numerous articles and hundreds of school children have viewed him over the years."
Why are the snails dying?
Snails were once numerous in Hawaii. But the populations have been decimated by invasive species, including rats, and habitat destruction.
Rats, which arrived on the island by ship, have been gulping down the largest snails. Meanwhile, the Rosy wolfsnail -- introduced as "biocontrol" more than 50 years ago -- and chameleons arriving in Hawaii as pets also have been eating native snails.
"As far as we can tell, the Hawaiian tree snails evolved with no predators, so they never developed defense mechanisms," Hadfield says.
What's more, snails are losing their habitat, and climbing higher up in the mountains of the islands.
"Pigs, goats, and deer degrade forest vegetation and fragment snail populations," coordinator for the Snail Extinction Prevention Program David Sischo wrote.
Melissa Price, an assistant professor at the University of Hawaii says she didn't realize how dire the situation was until one of her favorite snail species -- the Achatinella lila -- went extinct last April.
"They're rainbow colored, some striped, some deep black with an orange stripe around them," she said. On hiking trips, she would count snail populations. The Achatinella lila species went from 300 species three years ago, to one in April.
The last few are in captive breeding programs. "They're gone in the wild."
Because she's a younger professor in the field, Price said she wasn't a part of the teams of biologists who saw the snails migrate higher and higher into the mountains.
When she observed the snails on mountain tops during hiking trips, she said she didn't realize she was seeing the last ones.
"It's surprisingly devastating," she says. "They've been disappearing in the last two, three years. The rate of extinction is just really alarming for me."
"This is the story that we're seeing in every single species, we had to go up to the mountain tops to see them, when they would have been all over the island (in the past)."
And without the snails, Price said the forest is missing an important component.
"The (snails) eat the biofilm of leaves, they must help keep the trees healthy," she said. "They decrease fungal abundance on the leaf surface and increase diversity of the fungal community."
Biologists have saved some of George's DNA, Hadfield said, meaning the possibility exists that the world hasn't seen the last of the world's loneliest snail.
"Gene banks are being expanded all over the world," he said. "Somewhere, some day, maybe we can use this to re-establish a George."