In humans, mucus keeps tissues moist and also filters the air we breathe, trapping allergens and microorganisms before they can make us sick. On the other hand, nature has found more creative and fun purposes for the gooey stuff.
Some are fascinating – like the mucus bubbles that keep Australian animals alive during heatwaves – while others solve bizarre mysteries. Thanks to this sticky substance, we now know what makes frogs stick to trees, why sea sponges sneeze, and the truth about water stinging surfers around Florida.
Related: Top 10 amazing facts from the secret history of blood
10 Dolphins may communicate using mucus
Lots of things make dolphins great – their outgoing personality, the “smile” on their faces, and those cute chirps they make. But these pronunciations are a mystery.
They are not produced by the vocal cords in the throat but, instead, within the nasal passages. Lying directly under the dolphin’s blowtorch, clumps of tissue clump together up to 1,000 times per second and vibrate in order to make sounds. This is well known. But what scientists struggle to explain is how dolphins achieve such strange, high-pitched tones.
A computer simulation suggested it was all about mucus. In 2016, biologists adapted a model of the human vocal cord to recreate the sounds that dolphins make. The two-part common noise is bump and loop. At first, the team hypothesized that the bump came from clumps of tissue slamming against each other, and as they broke apart, a ring or squeak followed.
However, the mimics refused to produce the same high frequencies unless the scientists added a good dose of mucus to the mimic’s “dolphin” nasal passages. This strongly suggests that without mucus, dolphins would not be able to communicate or echolocation effectively.
9 Sea sponges sneeze for about 30 minutes
Despite having no brains, muscles, or nerves, sea sponges do have the ability to sneeze. During such an event, the sponge will expel blobs full of mucus and sand. It is not like a human sneeze, which is usually instantaneous. When the sponge has a spinning moment, it takes about thirty minutes to complete. Researchers have only recently discovered how and why sponges do this.
In 2022, new studies find that sponges sneeze to clean themselves. About 81% of the slime contains useless sediment. Scientists still don’t understand how these animals know when to sneeze, but when they do, here’s what happens. To get rid of unwanted particles, sponges express mucus through their pores, which then travel and collect along surface features that act as “mucus highways”. Sometimes, the sponge will contract and push the dirt-filled bubbles into the water.
A special group of scientists tracks and studies whales in an effort to preserve these giants. They must gather as much information as possible about the individual animal’s health and genetics, which in the past meant collecting samples by shooting darts at a whale. Desiring a less intrusive way to collect data, the researchers turned to mucus.
The result is an ingenious collaboration between robots, humans and whales. The researchers designed drones called SnotBots, drones that can collect a ball with petri dishes attached to its sides. However, the drones didn’t have to do anything but fly. The operator places the craft over the breaching whale, which then donates its mucus by exhaling air.
Without knowing anything, the whales help themselves — via their mucus — to help researchers learn more about the health of different whale populations, including humpbacks, blue whales, and orcas.
7 Catching sharks with mucus
Sharks have an almost uncanny ability to detect small amounts of blood from far away. In 2007, researchers discovered that mucus plays a major role. More specifically, to take advantage of this talent, sharks rely on a jelly-like substance in their heads full of salts and proteins.
The study found that “shark snot” only acts as an electrical conductor, and here’s how to help these predators hunt. Suppose, at a great distance, a fish is injured and bleeding. The salts in the leaking blood produce a strong electric field in the water that can be detected by sensitive cells in the shark’s skin. Once this happens, the positive charge travels through the gel to specific nerves. These nerves then activate electrical signals in the shark’s brain, alerting the animal to the potential meal.
Without this mucous substance, electrical signals cannot reach the shark’s brain. In contrast, without these cues, sharks would find it nearly impossible to detect a blood trail, let alone follow one.
6 Salamander goo hammers stitches
The giant Chinese salamander may not win any beauty contests, but it holds the noble title of the world’s largest amphibian. In addition, this creature produces mucus that is fast becoming a darling in the medical world. The mucus, which is secreted through their skins, makes a great glue for closing wounds.
Do not use the white goo in its raw form. Instead, scientists extract a bio-adhesive called SSAD by freeze-drying the raw mucus before mixing it with a saline solution. The resulting glue isn’t as durable as traditional methods—like staples and twine—but does offer an unintended punch in other areas.
In fact, SSAD does not cause allergic reactions like other bioadhesives. When it comes to closing wounds, reducing infection, inflammation, and scarring, and promoting healing, it also outperforms traditional methods of wound closure. SSAD also withdraws the fading process after three weeks, disappearing completely and eliminating the need for a removal procedure.
5 Snails recycle their mucous pathways
When a snail glides across the yard, its progress may seem easy. Definitely slow. But not really something that should be physically taxing on an animal. But in fact, producing the mucus that helps snails move takes more energy than swimming, walking, or flying. Needless to say, this can become a threat to survival at times when food is scarce.
Researchers have long suspected that snails use “sticky highways.” This occurs when the snail moves along a mucus trail left behind by another snail to avoid making too much of its own slime, thus conserving more energy.
But it was not until 2007 that this theory was confirmed when a sea snail was seen sailing along the hard work of other mollusks. The ensuing study also discovered that by playing Follow-the-Leader, the snails saved an enormous amount of energy because they only had to produce a small portion of the mucus that was required for an entirely new pathway.
4 Snotty divers to solve a marine mystery
At the bottom of the ocean, the sea floor teems with life. But as far as scientists can see, there just wasn’t enough food to support all of these creatures. Where was the missing food source? It had to be something plentiful, but the researchers couldn’t find it. For years, this mystery remained unanswered, but in 2005, they found the source, which was more bizarre than anyone could have imagined. Bottom feeders feed on something called sinkers.
Dippers are giant balls of floating mucus. Created by Bathochordaeus, giant tadpole-like larvae. These bubbles provide protection for the larvae and also filter through small portions of food that are the right size for these animals to eat. The finger-sized Bathochordaeus spins one ball at a time, which usually measures a yard in diameter.
It is estimated that these caterpillars create a new “home” every day. By the time you discard the old ball, the ball is already deflating and sinking. On their way down, these sinkers collect more food particles and sea creatures, essentially becoming food bombs for the hungry mouths below.
3 Super Glue Puzzle
In 2019, scientists visited the Wattagans mountain range in Australia when they found a strange sight. There, stuck on a branch, there was a frog. Something had stuck the amphibian so completely that the frog was covered in a sticky substance – and it was still stuck after a day. The only other creature nearby was a humble slug.
The frog apparently tried to eat the slug, which then responded with a mysterious glue motion. In fact, this type (red triangle slug) was known to produce only a thin, non-sticky slurry. So, how did the slug manage to “transfer” from a full frog to a branch? There was only one way to find out.
The scientists urged the animal to provoke it. Almost immediately, they discover that the creature can produce a second type of mucus. After one touch on her back, the area shrank and showered the nearby area with thick mucus. Not only is this an extremely rare display of defensive mucus, but scientists still don’t know how these slugs avoid getting caught in their own mucus.
2 Mucus bubbles to solve the mystery of the echidna
In Australia, two things shouldn’t go together: outback heat and the tiny, spiny animals called echidnas. Resembling a cross between a hedgehog and a shrew, these adorable creatures cannot survive if the mercury rises above 95 degrees Fahrenheit (35 degrees Celsius). In fact, studies have shown that they have a low heat tolerance.
But then, someone spotted a vegetable hedgehog sitting happily in a hollow log. Here’s the conundrum – the temperature of that record was about 104 degrees Fahrenheit (40 degrees Celsius). It wasn’t a strange occurrence either. Many of them have been observed exhibiting the same behaviour. Echidna does not pant or sweat in order to cool off, so how can it stay upright in conditions that are fatal to it?
Amazingly, in 2023, researchers discovered that urchin ants blow bubbles of mucus to stay calm. More specifically, they exhale a bubble that explodes above their noses. The mucus moisture then evaporates and cools the nose and blood, keeping the echidna’s body temperature safely below 86 degrees Fahrenheit (30 degrees Celsius)—even when Earth’s measurements reached as high as 116 degrees Fahrenheit (47 degrees Celsius).
1 The truth about water stingers
For years, surfers and snorkelers have faced a painful conundrum. In the shallow waters around Micronesia, the Caribbean, and Florida, the ocean caused such a stinging sensation that some people sought shelter on shore. The only suspect that was floating nearby was a so-called upside down jellyfish (Cassiopeia Ksamachana), but he was not near the victims when they were stung.
For lack of a better answer, people have assumed that this jellie may have lost an arm full of toxins. The severed appendage then floats towards an unlucky swimmer and hits them. However, scientists recently discovered that the truth was much stranger and riskier.
Yes, jellyfish was indeed responsible. But it has nothing to do with the torn claws. Instead, the animals throw up “snot bombs” filled with venom. These grenades can itch and burn human skin – which isn’t the worst thing that can happen to you at sea. But some fish are not so lucky. Jellyfish rely on the cell-destroying properties of their mucus bombs to kill other ocean life for food.