Which tropical fish carefully cleans parasites off larger fishes in coral reef ecosystems?

Cleaner Wrasse

Which snake species can fly or glide between trees? What Mediterranean seasonal snack consists of dried figs, nuts and spices pressed together? Who first proposed that disease could be caused by microscopic organisms (germ theory) in the 19th century? What desert covers much of Mongolia and northern China? What's the binary representation of the decimal number 5?