hairy frogfish
© Dimpy Jacobs / Lembeh Resort
It takes roughly 1/6000 of a second.
The speed of a hairy frogfish's bite is the result of a vacuum in its mouth that can suck in its prey in just 1/6000th of a second. It's so fast that even slow-motion video struggles to capture it.

In 2006, researchers also noted a swift predatory ant:
Biologists clocked the speed at which the trap-jaw ant, Odontomachus bauri, closes its mandibles at 35 to 64 meters per second, or 78 to 145 miles per hour - an action they say is the fastest self-powered predatory strike in the animal kingdom. The average duration of a strike was a mere 0.13 milliseconds, or 2,300 times faster than the blink of an eye. "Trap-jaw ants have fastest recorded strike in animal kingdom" at UCal Berkeley