LOS ANGELES, United States -- A mouse named after "Star Trek" actor Patrick Stewart is officially the world's oldest in captivity, a US zoo has announced.

Pat the Pacific pocket mouse -- the smallest species of mouse in North America -- bagged the title when he hit nine years and 209 days on Wednesday.

Officials from the San Diego Zoo Wildlife Alliance confirmed Pat was still going strong on Thursday.

The tiny creature -- whose longevity was recognized by Guinness World Records -- weighs less than six grams (a fifth of an ounce).

And unlike his namesake, who as Captain Jean-Luc Picard commanded the Starship Enterprise, Pat the Pacific pocket mouse is covered in hair.

The species got its name because of pouches in its cheeks, which are used to carry food and nesting materials.

The animals are found in coastal scrublands, dunes and riverbanks close to the Pacific Ocean.

Human encroachment left the species struggling and it was thought to be extinct until a tiny population was discovered in 1994.

Experts at San Diego Zoo Wildlife Alliance, whose breeding program has helped bring the Pacific pocket mouse back from the brink, said the little animals are vital to ecosystems because they distribute seeds and encourage plant growth through their digging.

"This acknowledgement is also a symbol of appreciation for species that people don't know much about because they're not charismatic megafauna, but are just as critical for ecosystem function," said Debra Shier of the wildlife alliance.

"These overlooked species can often be found in our own backyards -- like the Pacific pocket mouse."