Ticks Getting Hooked

What am I looking at?  

In the foreground is the mouthpart of an American dog tick, and to the rear is a lone star tick mouthpart. A tick’s mouth has two sets of sharp hooks to break through the host’s skin so the tick can insert its feeding apparatus, called a hypostome (1 and 2, respectively). In the center of a tick’s mouth are many spine-like barbs that point backward which help anchor it while it’s feeding on a host’s blood (3 and 4, respectively). There are also two mobile structures on the outside of the mouth, called palps, which move out of the way before a tick takes a bite (5 and 6, respectively). The colors in this image are a combination of autofluorescence and of blue and red fluorescence from the chitin-binding dyes Calcofluor white and Congo red.

Biology in the background  

A tick’s specialized mouthpart is the secret to its success as a parasite. The outermost structures of the mouthpart help a tick find a host, using sensory cues such as odor, body heat, moisture, and vibration. Ticks rest on the tips of grasses, leaves, and shrubs waiting for their next meal. Since ticks can transmit disease as they feed, they have gained a bad reputation among those who spend significant time outdoors.

The mouthpart of a dog tick is about 1 millimeter long, or roughly 13 times the width of a human hair. The mouthpart of a lone star tick is about 1.3 millimeters long, or roughly 15 times the width of a human hair.

Technique  

This image was created using confocal microscopy.