Federal prosecutors in San Diego say a man has pleaded guilty to charges he smuggled 100 pounds of dried sea cucumber into the United States from Mexico.

Sea cucumbers are leathery-skinned marine animals used in some folk medicine practices.

United States Attorney Laura E. Duffy says Cheng Zhuo Liu (chuhng joo-oh lee-oo), a resident of Chula Vista, admitted to tucking the sea cucumbers into the spare tire area of his car before crossing the border last October.

According to the US attorney's office, their market value was between $5,000 and $10,000.

The particular species Liu had is protected under international trade rules, and requires a permit for import.