slugs& Snails

by Ginny (P7)18/05/2011

What are they ?

• Snails and slugs belong to the animal group - molluscs.

• This group includes squids & octopus (and all the aquatic bivalves,i.e. cockles & mussels), as well as snails & slugs.

• Molluscs are soft-bodied animals, without internal skeletons, but themajority of them have some sort of shell which both supports andprotects the body.

• Snails and slugs belong to a sub-group called the gastropods (withinthe group of molluscs.)

• Gastropod means 'belly feet' and refers to the way the animals creepabout on their bellies.

• Slugs have descended from various groups of snails through thereduction or complete loss of the shell.

Snails• Snails have soft, un-segmented

bodies which are protected by ahard shell.

• The scientific name forthe garden snail is Helix aspersa.

• When a snail is disturbed,retreats into its shell.

• It also retreats into its shell &seals the entrance, in dryweather, to protect its body fromdrying up.

• A snail is most active at night &cloudy days. It does not like thesunshine very much.

• During very cold weather orwinter, snails hibernate in theground.

Source:http://qspace.library.queensu.ca/html/1974/136/images/snail01.gif http://www.kiddyhouse.com/Snails/

snails (on the outside )

Source: http://cnx.org/content/m19897/latest/snail.png

shell

eye

feeler

mouth

Breathing hole

Muscular foot

snails (on the inside)

Source: http://www.gireaud.net/images/snail_biology.jpg

Snails 2

• The eye of a snail is on the tip of thetentacle, a snail has two pairs of tentacleson its head.

• One pair is longer than the other pair, theeyes are on the longer pair.

• The shorter pair of tentacles is used forsmelling and feeling its way around.

• A snail moves by creeping on a flat footunderneath the body.

• The band of muscles in the foot contractand expand and this create a kind ofrippling movement that pushes the snailforward.

Source: http://www.kiddyhouse.com/Snails/

Snails 4

A snail is even able to move on very sharp pointed needles, knife, razors andvines without being injured because the slime helps to protect its body.

Source: http://www.odivinorum.com/11-strength.html

snailS eat…• Snails have a radula for grinding

up food.

• A radula is like a rough tongue /file with rows of tiny teeth that ituses to consume leaves andflowers.

• Snails can cause serious damageto crops.

• They eat living plants as well asdecaying plants. They also chewon fruits & young juicy plantbarks.

• The pond snail feeds mainly onplants like algae and microscopiccreatures that are found on thesurface of water weeds.

Source: http://www.pirx.com/gallery/albums/mollusks/radula.jpg http://www.kiddyhouse.com/Snails/

Eggs to Babies• Snails are hermaphrodites (both male &

female).

• Snails take approx. 2 years to becomeadults.

• After mating, each snail will search forsoft ground to lay its eggs.

• Snails lay their eggs in a nest in the soil.(2.5cm - 4cm’s in size).

• Snails can lay an average of 85 eggs &they hatch in 2 to 4 weeks, depending onthe temperature and moisture of the soil.

• Snails are most active in the months fromFebruary - October.

• The first thing a newly hatched snail doesis find food. They will eat what is left oftheir eggshell & will also eat any eggsthat have not hatched yet.

Source: http://farm4.static.flickr.com/3170/2894307647_826cbff41a.jpg http://www.kiddyhouse.com/Snails/ http://www.kiddyhouse.com/Snails/

Pond Snails

• Some pond snails have gills tobreathe in water.

• Those with gills will live at thebottom of the pond.

• Those that do not have gills, willcome up to the surface to breathe.

• These snails will live on thesurface so that they can come upto breathe easily.

• The pond snail reproduces justlike the garden snail.

• The only difference is that, thepond snail carries its fertilizedeggs with it and the baby snail willonly leave its mother when it ishatched.

Source http://www.kiddyhouse.com/Snails/

Snails

• Some snails are edible you can buypond snails from a fish monger inthe city.

• The flesh of the snail is supposedlyvery delicious.

Source http://www.kiddyhouse.com/Snails/ , http://www.kidsrecipe.co/category/whats-groser-than-gross/

why would people eat snails?

Probably in years of war / famine people were forced to eat things they wouldnot usually eat, due to lack of food.

People in the countryside were so poor / hungry that they probably decided toeat snails .

Popularity over the centuries has varied but people kept on eating them becausethey are quite tasty if prepared well i.e. with garlic and butter.

According to the ‘Larousse Gastronomique’, snails have been popular sinceRoman times. They were also included in a famous 14c. cookbook. the‘Menagier de Paris’,

The most common kind of snail eaten, apparently used to be one’s on vines andthey would have been readily available in wine country.

There lot of countries where snails are a traditional meal e.g. France (Escargot),some regions in Spain, Italy, Greece, England, Asia (they put snails in the soup),Africa (there are giant snails).

Source http://www.kiddyhouse.com/Snails/ http://wiki.answers.com/Q/Why_do_the_french_eat_snails

A super,A super,big guybig guy

• One of the largest species ofland snail is the Giant AfricanSnail which can grow to be38 cm from snout to tail, andweigh 1 kg.

Source:http://4.bp.blogspot.com/_8DfUOJtGfL8/S9_PdTC1CnI/AAAAAAAAEDc/hPu5vfD7YCE/s1600/giant-african-snail-1.jpg http://www.papuaweb.org/gb/foto/muller/ecology/09/05.jpg

Slugs• Most slugs prefer toeat decaying plantmatter. Slugs don’tactually do muchdamage.

• Slugs have also losttheir visceral humps(the part of the snailwhich is inside theshell).

• This means that thedigestive system andother internal organshave to be packedinto the head-foot.

• The mantle stillcovers part of thebody and, as insnails, it encloses thelung.

• A few slugs retain asmall shell at thehind end likethe Testacellabaliotidea, but theshell has beenreduced in mostspecies to a very thinplate or just a fewchalky granulesembedded in themantle.

• Slugs evolved fromaquatic animals.

• All land slugs andsnails have adaptedto breathing air bydeveloping a hole ontheir side whichexpands andcontracts to take inoxygen.

• The hole was formed,as their prehistoricgills disappeared tomake way for a set ofnew, lungs.

Image + Text source: http://www.jaxshells.org/aba.jpg http://www.the-piedpiper.co.uk/th11a.htm

A Baby Slug

Slugs(from The outside )

FOOT SKIRT Anus(Underthemantle)

trunkkeel

mantle

head

Pneumostome(Respiratory pore)

Optictentacles(eyes at tips)

GenitalOpening

PedalSlimeguard

Mouth(Radula)

Sensorytenacles

Slugs(From The Inside)

Source;http://snailstales.blogspot.com/2006/04/tiny-slugs-last-meal.html

Stomach

BuccalMass

Salivarygland

Rectum

Anus

Slugs

• Water is quickly lost from the slug's soft, moistand unprotected body so it has to live in dampplaces in the soil and among debris.

• It emerges only at night or on wet days. Aslug's organs of smell are in its tentacles andenable it to detect food several feet away.

• With no portable home into which they canwithdraw, the slugs are more susceptible todrought and to enemies than the snails,although they protect themselves to someextent with various kinds of mucus.

Source: http://www.the-piedpiper.co.uk/th11a(5).htm http://i.telegraph.co.uk/multimedia/archive/01627/slug_1627430c.jpg

Slugs

Source: http://www.the-piedpiper.co.uk/th11a(5).htm http://i.telegraph.co.uk/multimedia/archive/01627/slug_1627430c.jpg

• Many species are active all through the yearas long as the weather remains kind.

• During very dry/cold weather they tunnel deep down into the soil.

• Some slugs live most of their lives in the soil, but most of them aresurface feeders & they come out to feed at night or when the air is dampafter rain.

• Slugs dislike rain falling on them, but often emerge in their thousands assoon as it stops.

• If you look closely at a keeled slug you can often see lots of tiny animalsrunning all over their bodies.

• These tiny animals are mites and you will see them on the keeled slugs.

• The slugs don’t mind their tiny mites and don't even cough when thesepassengers scuttle in and out of their breathing pores.

• Although slugs have descended from snails, they have not all descendedfrom one group of snails i.e they are not all closely related.

Slugs

Source: http://www.the-piedpiper.co.uk/th11a(5).htm http://i.telegraph.co.uk/multimedia/archive/01627/slug_1627430c.jpg

British slugs belong to 3 distinct groups:

• shelled slugs,

• keeled slugs

• round backed slugs.

There are approx. 24 British species of slugs.Half of these turn up in the garden over time.

Thanksfor watching

Background image source: http://wallpaper-s.org/11__Raindrops_on_a_Leaf.htm