A new look at a tick’s mouthparts shows how the arachnid saws its way through skin and hangs on for up to a week. The castor bean tick Ixodes ricinus, a European species that carries Lyme disease, faces an engineering problem: Its needlelike mouthparts are good at piercing but useless for hanging on during long periods of feeding. And unlike some ticks, this species does not make a cement to anchor itself to its host.
Using a scanning electron microscope and videos to magnify their subjects thousands of times, German and U.S. researchers found that the ticks use a two-step process to ratchet their way in. First a pair of chelicerae (the winglike structures at top) telescope out to pierce the skin, pumping alternately like engine pistons to gain a foothold. Then the chelicerae switch to a breaststroke motion that draws in the barbed tonguelike needle, or hypostome (center). The tick’s method may inspire engineers to mimic it, the team reports October 29 in the Proceedings of the Royal Society B.
TICK’S BITE A close-up view shows the motions of a tick’s mouthparts as it pierces the skin, followed by an animation detailing how the tick establishes a firm hold. Credit: D. Richter et al/Proc. Royal Soc. B 2013