Tiny freckled shrimp hang out on a Korean pen shell—a type of saltwater clam—in an undated picture.
Called pen shell shrimps, the tiny crustaceans—previously known in Japan and Australia—were only recently observed in South Korea, scientists announced in early September.
Pen shell shrimps live in symbiotic, or dependent, relationships with clams, explained Kim Min-Ha, manager of the Korean indigenous-species project at the South Korean National Institute of Biological Resources.
"We think that the clam provides shelter for a shrimp," Min-Ha said in an email interview.
The institute's ongoing project to catalog animal and plant diversity on the Korean Peninsula (map) began in 2006 and will run until 2014. In the latest round of expeditions, scientists discovered 117 new species and documented 15 that had never before been found in South Korea.
(See pictures of a "glass" crustacean and other new species found recently on the Korean Peninsula.)