A cat's paw can also be used to unlock the iPhone 5S. (Darrell Etherington/TechCrunch)

The iPhone 5S fingerprint sensor has been both praised and criticized by techies, but one thing that people weren't anticipating was how Apple's latest smartphone applies to their pets. A video posted on TechCrunch shows that even a cat's paw can unlock the device.

Darrell Etherington, a writer for the tech news website, said that one of his colleagues, Natasha Lomas, came up with the idea. "I had the phone to review, she had a cat, and said that it was something we could try," he told ABC News.

The cat's pawprint was not masquerading as Etherington's. Instead, the cat (whose name is kept secret by TechCrunch employees) had its own profile set up on the iPhone 5S. "The registration process took a little bit longer than it would a human's fingerprint."

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In addition to a longer registration process, the cat also encountered more authentication errors trying to unlock the iPhone even with a user profile already set up.

"It seemed like there wasn't as much tolerance, like if the paw were at a different angle than when the cat first registered," said Etherington. Eventually, the cat's paw was able to unlock the phone reliably.

Apple declined to comment, or purr, when reached by ABC News.

Etherington has also used other non-finger parts of his body to unlock the phone.

"I've tried with the underside of my forearm and the heel of my palm, so long as it has a recognizable pattern," he said. "It has to be alive, but really it's any type of exposed skin."