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See how a jellyfish stings in microscopic slo-mo

Forget Shark Week. The box jellyfish is way more dangerous, and its mechanism for injecting venom can only be witnessed with a microscope.

Stinger close-up
The harpoon-like stingers extend from the tentacle. Video screenshot by Amanda Kooser/CNET

Destin Sandlin is already a rocket engineer, but he's still on an ongoing mission to keep learning and share knowledge through his "Smarter Every Day" YouTube show. The latest episode involves a quest to witness something that can't be seen with the human eye: how a jellyfish stings.

Sandlin describes the box jellyfish as the "most venomous animal in the world." He likens the defence mechanism of the jellyfish to having a bunch of tiny hypodermic needles attached to its tentacles. All it takes is brushing up against the jellyfish's dangly bits to get injected with the creature's venom.

Actually seeing a box jellyfish's sting in action requires a microscope combined with a high-speed camera. Sandlin went to James Cook University in Australia to meet up with professor Jamie Seymour, an expert in jellyfish and other venomous animals, which qualifies him as a toxinologist. Researchers at James Cook University are working on coming up with ways to counteract the potentially deadly box jellyfish venom, which acts as a cardiotoxin, impacting the heart.

Since an actual jellyfish wasn't available, the scientist used a tentacle from a sea anemone, which uses the same mechanism. Seymour triggered the sting by touching the tentacle with two leads from a 9-volt battery and captured the results.

The video is fascinating. Miniscule needle-like protuberances extend from the tentacle, like a sea-creature version of Pinhead from "Hellraiser". It only takes about 11 milliseconds for the flexible bio-needles to deploy. Venom squirts out from the tips.

Seymour was impressed with the captured footage, which he has been questing after for years. "We've never had the camera technology to actually do it at this level before," he said.

The slo-mo video of the sting mechanism at work should give ocean lovers a new appreciation for how the box jellyfish's defense functions, and reinforce why it's a good idea to stay way clear of the creatures.