This glowing whale-size, worm-like animal is one of the weirdest things in the ocean

Nope, the strange underwater thing in the image below isn’t an inflatable tube man swallowed by the ocean.

It is a pyrosome.

Photo: YouTube user BBC

Pyrosomes are so rare that, for most underwater divers, they may as well be unicorns. They have only been caught on film a few times.

Of all of the strange creatures in the ocean, the giant pyrosome is certainly one of the strangest.

Pyrosomes are shaped like hollow tubes that are closed at one end.

Photo: YouTube user New Scientist

The long tube in the picture is one pyrosome, but is actually made of dozens of animals that reproduce by making exact copies of themselves, then weaving their tissues together to form one long tube. These clones are referred to as zooids.

Photo: YouTube user BBC

This one, seen drifting through the water in the image below, was found in 2011 by Michael Baron of Eagle Hawk Dive off the coast of Tasmania.

Photo: YouTube user BBC

These giant colonies start out as a single zooid. As they make copies of themselves, the “animal” gets bigger. The final size of the colony depends on its species and age.

Photo: Nick Hobgood

The individual zooids are tiny — smaller than a jelly bean — and glom together with a “gelatinous tunic.”

Photo: Bill Stohler

They can grow to the size of a whale, though most are much smaller. The biggest ones can fit an entire human inside.

Photo: NOAA

Never try to swim in one, though. Karen Gowlett-Holmes, of Eagle Hawk Dive, says she found a dead penguin inside a pyrosome. It probably swam inside, got stuck, and drowned.

Photo: YouTube user BBC

Zooids in a pyrosome survive by filtering the water from the outside through their bodies, eating tiny animals called plankton in the process. Used water shoots into the inside of the pyrosome tube, where it flows out the large hole at one end.

Photo: YouTube user blennywatcher

The communal squirting of water creates jets that propel the tube through the ocean — though they primarily use ocean currents to get around, since the jets are so weak. But they are the only animals we know of that move exactly this way.

Photo: YouTube user MBARI

They’re even bioluminescent, so they can flash a blue-green, white, or pinkish light that’s visible from several meters away.

Photo: YouTube user blennywatcher

And yes, they are as fluffy and soft as they look. The few divers who have actually touched them say they are as soft as a feather boa. Michael Baron, of Eagle Hawk Dive, told the BBC: “When I touched it it didn’t really react. It felt like a soft jelly-like substance.”

Photo: YouTube user BBC

Not that you should touch them, of course. You could either disturb them or discover you are actually touching the long tail of a venomous jellyfish.

Photo: NOAA

Scientists don’t know too much about these gentle giants, since the large ones are pretty rare.

Photo: YouTube user New Scientist

Some people think the ocean may actually be filled with them. They live in warm tropical and temperate waters.

Photo: YouTube user blennywatcher

Another similar creature called a salp roams the oceans as well, but they are not bioluminescent. They also don’t form tubes but link up in chains.

Photo: YouTube user Eagle Hawk Dive

The salp also moves by pumping water through its body in pulses, rather than continuously pushing water through as the pyrosomes do.

Photo: YouTube user Eagle Hawk Dive

Robert Ferris contributed to a previous version of this post.

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