Slime: protector, lubricant and glue

GOO, GUNGE, GUNK... WHILE THERE are many names for the stuff that makes things slippery or sticky, slime isn't a single material but a label for a variety of substances with similar physical properties. Those qualities are desirable to many living things, which is why slime is made by such a wide range of organisms.

- JV CHAMARY

What is slime? 

There's no exact definition: the word reflects characteristics. So you could say (perhaps unhelpfully!) slime is any substance that feels slimy - it's something that will slip or ooze from your hand when you hold or squeeze it, for instance. The best-known slime is mucus, a material that covers many external and internal body surfaces. Mucus keeps an amphibian's skin moist, for example, and prevents the lining of a mammal's lungs from drying out. Technically a viscous (thick) liquid, mucus doesn't flow in its steady state and behaves like a solid - it's a gel.

How does mucus protect animals?

The gel's main function is to serve as a barrier that lines a surface to protect an animal's outermost cells from infection or damage. In the human body, snot (nasal mucus) captures invaders such as viruses, while the mucus within the digestive system stops your stomach digesting itself.