The secrets of citrus micro-jets, captured in high speed

Peel an orange or a lime and then bend a section of fruit until the liquids squirt from the skin at 30 feet per second. At what point did the skin give way? Where did the micro-jets shoot? Why did the skin of citrus fruit evolve to do this? This is what the University of Central Florida’s Andrew Dickerson and his team have been studying. From The New York Times:

The scientists used high-speed videography to track how the process works and found sacs of oil in the relatively soft part of the skin just below the more rigid outer layer. They used pliers to bend skin of several citrus fruits and found that at a certain point, the stress on the skin causes a break and the oil reservoir empties in a burst.

Micro-jets are found in other plants and in animals as well, such as spitting termites and spiders. Why citrus plants show this action when the skin is bent in an extreme way isn’t known, although the oils are toxic to some insects, plants and microbes.