Every now and then a video of an animal doing what an animal always does takes the Internet by storm, purely because it's not how people expected that animal to behave. 

We've had the pufferfish video that went viral because everybody thought they filled themselves with air (they do not), and we've had the video of swimming seashells that went viral largely because people didn't picture them swimming at all.

Now to that list add starfish, casually taking a stroll down a beach.

 

The video was captured in the Outer Banks of North Carolina in early October 2012, but has recently re-emerged (like a starfish from the ocean) on Reddit. Other videos show the same behavior, above and below water.

So what's going on here?

Basically, starfish are not the sedentary creatures you're all picturing them as. They may look pretty static, but some species can walk quite speedily (well, relatively speaking). Adult sunflower sea stars, for instance, can move at the breathtaking speed of 1 meter (3 feet) per minute using their 15,000 tube feet that cover their underbelly. Other species, like the leather star, can only go at a sluggish 15 centimeters (6 inches) per minute.

Having descended from bilateral animals, starfish move like bilateral animals (e.g. crustaceans or spiders) with certain legs acting as the "front" of the animal. 

The tube feet look like suction cups, but the starfish actually grip the floor using adhesive chemicals. The tube feet move in a wave, with one section of the arm attaching using chemicals as another area of the arm releases its grip (using other chemicals to detach itself from the surface).

They should not be walking around on land at all, however. They breathe by absorbing oxygen from seawater, and will quickly suffocate when removed from the water. 

If you're worried about the starfish in the video, don't be.

"WE PUT THE STARFISH IN THE WATER," Zeb Hallock wrote on YouTube.

"We did not take them out of the water, we found them walking/stranded on the beach at low tide and put them back into the ocean or tide pool. I took the video before putting that one back in the water because it was such an unusual sight. All the starfish (sea stars) we found alive on the beach were still alive when we put them back in the water."

There's a chance that the starfish is still alive, in fact, as they can live around 35 years, walking around on the sea floor.