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.
Recorded in South Korea for the first time, the small red crab Liomera margaritata (pictured in a photo released in early September) has flesh that is "almost certainly poisonous" to predators, said Min-Ha said of the South Korean National Institute of Biological Resources.
Even so, "these crabs are only algal feeders. It doesn't use its poison," she added.
Previously known in Madagascar, Vietnam, Thailand, Indonesia, and Japan, the 0.7-inch-long (1.7-centimeter-long) crab was recently spotted in the waters near South Korea's Jeju-Do island (map).
"They are slow-moving crabs, usually hiding in rock crevices," Min-Ha said.
With their transparent, ghost-like bodies and penchant for nighttime activity, Korean glass shrimp (pictured, a shrimp in a photo released in September) can be hard to spot, according to Min-Ha of the National Institute of Biological Resources.
That elusiveness may help explain why glass shrimp—though already documented in Hong Kong and Japan—were only recently found in South Korea, near Jeju-Do island.
The colorful new Rhamnus plant bug (pictured in a photo released in September) is 1 of 17 new insect species recently discovered by South Korea's National Institute of Biological Resources researchers.
The tiny crustacean Cymbasoma reticulatum was found near the port of Ganggu in the South Korean city of Yeongdeok.
The alien invader, which hails from the Mediterranean Sea, was inadvertently transported to the Korean Peninsula in the ballast water of cargo ships, according to Min-Ha of South Korea's National Institute of Biological Resources.
"The effects of these invasive species [on native wildlife] are not known yet," Min-Ha said.