The Buffalo Zoo's two-toed sloth died Tuesday from natural causes.
Ethel was 31, more than doubling the median life expectancy of 15 years for two-toed sloths.
Ethel came to Buffalo in 1987 from the Salisbury Zoo in Salisbury, Md. She lived with her half-sister Mini for more than 25 years until Mini's death two years ago.
"Ethel was loved by all the keepers here, and was a favorite of visitors to the zoo," said zoo spokesman Christian Dobosiewicz. "She lived a long and healthy life here, and will be greatly missed."
Sloths, which are native to South America, are nocturnal. For that reason, Ethel was often asleep in one of the corners of her enclosure when zoo visitors saw her.