Image Credit

Are you about to be eaten alive by a giant slimy alien?  No, this is a great macro photograph of a snail – up close and personal!  Perhaps we are the aliens!  Snails that live on land have been around for quite a while, around six hundred million years which puts our species to shame!  Although there are still many more species of snails that live in water, it is the land snail that most people know well.  Many shudder at the thought of the sliminess of the creature, others have nightmares about them.  However, there are many aspects of snail life that will surprise!  Seen up close, too, the shells of these gastropods are often things of exquisite beauty.

Image Credit

The largest land snail is the Giant African, which can measure up to thirty centimeters in length.  It can also be eaten and is a fantastic source of protein.  A native of East Africa, many people now keep these as pets, although it is illegal in the United States.  When bred in captivity they are easy to keep and free from parasites and disease so are quite harmless. You may not like the idea of one crawling over your foot, however!  Where sold as delicacies, they are often cooked, sliced and canned.  Yummy!

Image Credit

Most snails have one large foot and this is what a lot of people dislike as it needs to be moist to move.  This means that the snail lubricates its foot with mucus and leaves a trail behind it.  The mechanics of the foot, however, are a triumph of evolution. 

Image Credit

The muscles contract in wave after wave which moves centrally down the foot, enabling it to move.  Grab a snail and stick it on some glass to see this movement in action – it is almost hypnotic! The mucus makes sure that there is little or no friction to hinder the snail but it also makes it very difficult for the snail to be injured.  In this way it is quite possible for a snail to move comfortably over a razor blade – but don’t try this at home.  If you still live with your parents they may not appreciate it!

Image Credit

Snails are good mathematicians even though they may not appreciate it themselves.  As they grow, so do their shells which are made from calcium carbonate.  The formation of the shell is what as known as a logarithmic spiral.  This is where the distance between its spirals increases progressively.  Although the snails do it approximately, logarithmic spirals can be represented by complex mathematical formulae.  Basically, the size of the spiral gets bigger and bigger but its shape remains the same.  Amazing!

Image Credit

So what stops a snail from growing to gigantic proportions?  Apart from the necessities of its environment, when a snail species reaches its full size then a thick lip grows at the place where the shell opens.  This means that it is time to find a friend and reproduce!  So, on small immature snails you will not see a lip – you can tell if they are babies whatever the species!

Image Credit

Another thing about snails that a lot of people find frankly unappetizing is their tentacles!  Even the word can send a shiver down many a spine as they imagine being wrapped up by these appendages and devoured as lunch a short time later.  Most snails living on the land have two sets of tentacles.  The upper pair are their eye stalks – or if you want the scientific name, their ommatophores.  They are usually about three quarters the width of the eyes which is why you get the bulge at the top.  The lower pair is used to smell out their food.  Snails can sense vibrations with these tentacles, which can retract when the snail perceives danger, but snails cannot hear.

Image Credit

Most terrestrial snails are herbivorous which means that they eat plant matter, so the fear that the snail may start eating you if placed on your hand (or elsewhere) is wholly unfounded. One or two land snails are carnivorous, but they will still not attempt to eat a live human! In fact, although land snail live virtually everywhere – from high up in mountains to the heat of the dessert the species that we see around us are found close to our homes.  You could almost say that they like the company of humans, but most scientists would refer to then as anthropophilic.

Image Credit

Have you ever heard a snail eat?  Well, you can!  The snail attacks it food using the radula, which is made of tiny hooks.  In this way it doesn’t really bite in to food, but rather scrapes at it.  The bits that it tears away are then sent straight to the digestive area (known as the tract). 

Image Credit

So, next time you find yourself next to a large land snail (in a very quiet area!) see if you can hear it scraping away at its lunch!  It won’t mind – its brain is so simple (even though it is divided in to four separate areas) that it will not sense you as a threat.  Snail can learn by association though!  Think of Pavlov and his dogs, dumb it down a lot and you are in the right ball park!

Image Credit

Many species of snails will sit out the winter in hibernation.  They will also, during long hot summers, occasionally estivate.  Estivation is not something of which many people are aware – but it becomes self-explanatory when given its common name – ‘summer sleep’.  A snail will go in to a summer sleep to avoid the high temperatures and to risk becoming too dry (dessication). 

Image Credit

For many snails, estivation will save their lives as to keep their shells in tip top condition they need a lot of calcium and in dry times this can be harder to come by.  The snail will seal itself in by drying out a layer of mucus over the entrance to its shell.  This is called an epiphragm and many people, when they see a snail like this, believe it to be dead.  No – it is only sleeping!

Image Credit

All terrestrial snails are hermaphrodites.  This means that they have the organs to reproduce which are normally associated with the male and female separately, it does not mean that they can mate with themselves!  What it does mean with land snails, however, is that when you see a pair of snail mating, that they are inseminating each other.  In other words, snail A will fertilize the eggs of snail B and vice versa!  They will then lay anything up to a hundred eggs each.

Image Credit

Snails do not lay their eggs on plants like other species such as butterflies.  They lay their eggs in loose topsoil.  This is one of the reasons they like living close to us – our farming and general plant growing means that the soil is often turned and so is nice and loose for the eggs to be laid – way down – up to ten centimeters below the surface.  The eggs will hatch around three weeks later.  Many land snails are fecund in the extreme – they will mate and lay eggs around once a month.  No wonder gardeners and farmers don’t like them much as that means, collectively, they can scrape their way through a whole lot of food!

Image Credit

When the baby snails emerge they will eat the remains of their eggs as it is a great source of calcium and they need this for their shells to grow.  For a few weeks they will look transparent to the human eye, but then their shells will turn to the usual color.  It has been recorded that herbivorous snails will eat any unhatched eggs that are around which is a form of cannibalism! 

Image Credit

When the shell turns color they effectively look like tiny versions of the adults (even though sometimes the body looks too long to go in to the shell!).  It will be at least a year before they are ready to breed themselves.

Image Credit

Snails are eaten in many European countries – the most familiar being the French escargot where they are served in garlic and parsley sauce.  To get the snail ready for the pan they must go through, first of all, a nil by mouth system where they are only given water for a few days.  After that they are fed on only flour or water for a week.  This is to clean out the snail, effectively, because otherwise they would be cooked with all their waste product still within and so would not taste very nice!  Other snail eating cultures include Greece, Spain and Italy although lesser known traditions do exist in northern European countries such as Germany and the United Kingdom.  They must be cooked properly as if not they can cause a form of meningitis!

Image Credit

Whether you love them or loathe them, snails are everywhere!  So, if you view them as a pest, a pet or a tasty treat, spare the occasional thought for the snail – there is more to the