Slime is produced by a variety of animals. In many, including humans, it serves a protective function, forming a barrier between the inside of the body and a world of germs.
In the gastropod molluscs, slimes are used for lubrication, adhesion, signalling and protection against abrasion and pathogenic or predatory attack.
Chemically, snail mucus is a watery gel containing a small proportion (less than 10 per cent) of glycoprotein polymers – large, complex molecules that link together to give the slime its distinctive properties.
Snail slime is secreted by glands located all over the body, though the largest, and that responsible for the silvery trails, is at the front of the foot. When resting, snails produce enough mucus to glue themselves to a substrate and create a membranous seal called an epiphragm covering the opening of the shell.
The seal dries gradually and can become quite crispy, while the snail inside stays moist. Medical researchers have taken slug and snail slime as the inspiration for new surgical glues with the ability to bind wet, moving tissues without damaging them.
Do you have a wildlife question you’d like answered? Email your question to firstname.lastname@example.org or post it to Q&A, BBC Wildlife Magazine, Immediate Media Company, Eagle House, Colston Avenue, Bristol, BS1 4ST.