Until recently, prehensile tails came in 2 basic designs: the elephant trunk - just muscles, no bones - and the monkey tail, in which muscles flex a series of bones. But now a us scientist, Kevin Zippel, has discovered a third design in the tail of a lizard called skink found on the Solomon Islands,in the South Pacific (Science, Vol 26, 5176).

The skink's t(I consists of a series of cone-shaped muscles stacked on top of one another and covered by a sheath of spirally wound fibres. This allows the tail to bend in any direction, and for one part to stay rigid while another part flexes.