Today’s Wonder of the Day was inspired by Zoe from Christchurch. Zoe Wonders, “Why are snails and slugs so slimy?” Thanks for WONDERing with us, Zoe!
If you made a list of the top five creatures you'd have for a pet, what would you choose? Many would probably choose a dog, since a dog is man's best friend. Others might choose a cat, because they're so cute and furry.
But what other creatures would round out your list? A hamster? A gerbil? A tank full of fish? A turtle? How about a snail?
Some of you may be thinking, "Who would have a snail for a pet?" Other than SpongeBob SquarePants, of course, there probably aren't many of our Wonder Friends who have snails as pets. After all, they're not furry and cuddly, and they move really slowly. And then there's also the slime issue.
If you've ever seen a snail (or its cousin, the slug) in the wild, you've probably noticed that tell-tale trail of slime they leave behind as they move slowly across the grass or a leaf. Can you imagine constantly finding trails of slime across your bedroom floor or pillow? Yuck!
So what's up with all that snail slime? Snails are gastropods. Since "gastro" means stomach and "pod" means foot, a snail is essentially a "stomach foot." This description makes sense, since a snail's body is like one long foot with a mouth on one end.
Snails produce slime, which is a kind of mucus, via a special gland on the front of the snail's foot. Scientists initially thought that the purpose of the slime was to enable snails to move. Over the years, however, researchers have learned that snail slime is a special substance with unique properties and several purposes.
Snail slime has the consistency of a liquid gel. At rest, it's solid and sticky. Under pressure, though, it liquefies and acts as a lubricant.
Although their slime definitely helps them to move along more efficiently, snails don't need it to move. They have muscles on the underside of their feet that generate pulses that propel them forward.
As they travel on the slime they produce, the slime helps them to stick to whatever surface they're on while their muscles are at rest. As their muscles contract and push down to propel them forward, however, the slime becomes more liquid and makes movement easier.
Slime is particularly handy when snails climb vertical surfaces and even travel upside-down. In these instances, the slime's sticky properties help snails cling to surfaces, seeming to defy gravity!
Snails constantly produce slime, even when they're not moving. When they do move, they leave a trail of slime that can appear as a silvery track on various surfaces. When they're not moving, the slime serves another important purpose.
In addition to helping them move, their slime helps to protect snails' skin from environmental hazards, such as sharp objects, bacteria, and the Sun's ultraviolet rays. In dry weather, snails can curl up in their shells and seal themselves inside using their slime. This helps them to stay moist and comfortable even when the weather threatens to dry them out.