Studying the fastest animal body parts isn’t just a matter of having interesting scientific trivia. It provides insight into how evolution can push limits, what tradeoffs are required for speedy motion, and how predator-prey relationships work in the animal world. Dracula ants, for instance, have come up with an apparently novel way to overcome to the problem of muscles. Muscle power can only get you so far—eventually, skeletal muscle reaches a point where it just can’t move any faster or with more force. As the authors point out, many arthropods have found ways to overcome that problem by evolving biological springs and latches. You can form a very simple one with your fingers when you snap. The friction between your middle finger and thumb acts kind of like a latch, allowing tension to build up in your hand. When the pressure becomes too great, the fingers spring past each other far faster than you’d be able to rub them together with muscle power alone.