EducationalGifs

"When you touch it, it explodes"

Nitrogen Triiodide is an extremely sensitive explosive compound that, when dry, can be detonated by the lightest of touches or vibrations. 

From The Physics Girl: “What happens when you drop a perfectly balanced stack of balls? And how is the result like a supernova? The classic momentum transfer demonstration, at the next level.”

With a tail that can be long as its body, the Thresher Shark attacks its prey with violent whip like motions.

This behaviour has been suspected by researchers, but only recently has it been caught on film. The tail is used to stun, maim or even kill the prey, with the shock-wave created by the momentum also stunning surrounding fish.

It is thought to be an evolutionary adaptation as these sharks hunt mainly smaller fish such as sardines. This makes the whip mechanism much more efficient at catching multiple fish with a single blow, as opposed to one fish at a time the shark would tend to catch with its jaws.

Sepios

Inspired by the cuttlefish these students at the Swiss Federal Institute of Technology built a nautical robot that mimics the locomotion.

Sometimes, against a uniform, bright background such as a clear sky or a blank computer screen, you might see things floating across your field of vision. These “floaters” are not any kind of external objects, nor are they alive. Rather, floaters are tiny objects that exist inside the eyeball, and cast shadows on the retina - the light-sensitive tissue at the back of your eye.

To learn more about floaters, watch the TED-Ed Lesson What are those floaty things in your eye? - Michael Mauser