Look at a snail, and you'll see that they don't have any "feet," right? This assumption is incorrect as snails do have a singular foot that helps them to navigate their environment, just as these appendages do for humans.
Still, there are vast differences between human feet and a snail's foot. Discover these key differences along with an array of fascinating facts about a snail's "foot" and general composition.
Do Snails Have Feet?
Snails don't have feet, but they have an appendage called a "foot." This foot helps them to move around their environment - just like our feet help us to do the same, but that is where the similarities end. Their "foot" is entirely different from a human foot; it is a muscular, mucus-covered mass at the base of their body.
When a snail moves around, a large section of its body extends out of the shell to form this flat "foot," primarily used for movement (which is why we call it a foot). The scientific name - Gastropoda - literally means a "belly-footed" animal.
A snail's foot comprises several muscle layers which move in a wave motion to assist travel; the slow wave motion of a snail's movement ensures that part of its body always stays in contact with the surface. As the snail moves, this foot also secretes mucus to help push the snail forward as it contracts its muscles.
This slime has an impressive set of physical properties, including hygroscopy, which attracts water and prevents snail desiccation. This mucus may help to ease the snail's movements, but conversely, it can also increase suction. It helps a snail to stick to almost any object, including glass, making it easier for them to scale vertical surfaces and even "walk" upside down.
How Many Feet Do Snails Have?
A snail has one foot, which is a muscular mass at the base of its body. This foot does have some similarities to a human foot: it possesses muscles and helps the organism move. Still, there are many ways that the foot is different from what we call a foot. Our feet have bones and are attached to other limbs - our legs. In contrast, a snail's foot secretes mucus to help it move around and isn't connected to other limbs.
How Does a Snail's Foot Work?
Our feet work based on information and messages supplied by our brains. Some are voluntary, such as us deciding to go for a walk while our brain relays that message to all necessary body parts. Others are involuntary, such as lifting your foot off a hot surface because of a pain response. Still, if snails don't have brains, then how they can control their movements?
Snails might not have a brain like ours, but they have a primitive set of neurons called ganglia. This "brain" is far simpler than the complex organs found in mammals, reptiles, and birds, but it is still capable of associative learning. Within this collection of ganglia are two pedal ganglia that support the muscles of the "foot."
They may only have two brain cells, but research has shown that these cells are capable of making complex decisions. And their associative thinking is excellent, which helps them to remember where they've been before. In addition, the snail's body has nerves that alert the snail to touch or pain, allowing them to retreat its shell in dangerous situations.
What Kind of Movements Do Snails Make?
You might assume that an animal with a foot would walk, but this is not the case for snails, whose expansion and contraction create more of a sliding motion.
What might surprise you is that snails can jump! Not all snails, just a particular species aptly named "jumping snails" This is quite a feat without legs and can take five-six times more oxygen than regular movements. These snails jump by using their foot to power their body muscles, propelling them 1-2 inches at a time.
Certain marine snail species can even swim with a fin-like growth along the foot, which helps them to move in a swim-like motion.
The Anatomy of a Snail
The foot isn't the snail's only unique feature. Externally, their body consists of two main parts: the shell and the soft, fleshy part. Their shells are solid masses of protein and calcium carbonate with a spiral that develops from a single whorl at birth. Their body is soft as it lacks a skeleton and possesses a viscous texture. Still, they do have an outer layer of tissues that helps to protect internal organs.
Two pairs of tentacles act as eyes and a nose; the upper tentacles are longer and have eyes at the top. These eyes have a similar makeup to a human's, complete with lens, retina, and optic nerve - but a snail's sight is not good, and they can only sense light changes. The shorter tentacles beneath are used for taste and smell. A snail's head also houses a mouth complete with a radula. The radula consists of sharp rows of teeth that help the snail scrape up food.
The muscular ventral foot is located at the base of the snail; it is the part of the body which comes into contact with whatever surface they're moving across.
Unlike many other animals, a snail's internal anatomy isn't divided into different sections. Instead, all their organs are in one solid central mass protected by the shell. This includes vital organs such as the heart and lungs. However, only terrestrial snails have a lung, while aquatic snails have gills instead.