Eye of the Dragonfly

What am I looking at?

These images show several views of the repeating units, called ommatidia (1), that make up the eye of a dragonfly. The colors you see in these images are the result of a process called fluorescence, which happens when you shine a laser onto a sample under a microscope. Different structures in the sample are stained different colors – the protein actin is green (2), the nuclei are red (3), and the chitin is blue (4).

Biology in the background

Each one of the hexagons you see is basically a “mini eye,” meaning it has the ability to focus and detect light on its own. While these eyes cannot see in as much detail as a human eye, they are very good at detecting movement. Their enhanced visual field and ability to detect movement help insects avoid predators and catch their prey.

These sections come from an area on the top of the dragonfly’s eye called the functional fovea, where the ommatidia are larger and almost parallel to each other; in the rest of the compound eye, the ommatidia are smaller and are arranged radially (spreading out from the center). The functional fovea provides the highest visual resolution, and the dragonfly uses it to track its prey.

Each of these hexagons is about 22 micrometers across, or roughly three times smaller than the width of a human hair.

Technique

These images were created using a confocal microscopy.