Snails

Snails

Fig. 1: The Brown lipped snail (Cepaea nemoralis) has a surprisingly aesthetic appearance and diversity in its stripes. Fundamental aims of the acti...

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Fig. 1: The Brown lipped snail (Cepaea nemoralis) has a surprisingly aesthetic appearance and diversity in its stripes.

Fundamental aims of the activities

The Snail The snail he lives in his hard round house, In the orchard, under the tree: Says he, „I have but a single room; But it‘s large enough for me.“ 

Anonymous

• To discover diversity among native snails • To reduce prejudices and feelings of disgust • To recognise the role and usefulness of snails in an ecosystem • To awaken interest in snails as examples of molluscs

Snails Snails are very suitable for use in class because of their slow way of moving and because they are very easy to keep. They are easy to find and to observe. Most city children know something about snails, too. The starting point is therefore the immediate environment and the direct experiences of the pupils. The aesthetic appearance and diversity of snails stands in opposition to their very low popularity. When they think of snails, many people associate them with the endless fight against the seemingly invincible slugs in their gardens. Our relationship with this interesting and extremely diverse group of animals is often reduced to that of enemies. The cause of this is mainly the Portuguese slug, which reproduces in large numbers, and a few other slug species. An important theme of the “snail activities” is therefore awareness when dealing with other living creatures. The thoughtless treatment of snails in particular by young people should encourage us to show

Snails 

our pupils the interesting and beautiful aspects of these animals. This group of animals is often completely misunderstood and now endangered, and at the same time it is an example of how we are dealing with our living environment. The sole benchmark “useful” versus “useless”, from the perspective of humans, separates species into the questionable categories “worthless” and “valuable” (because they are cute or useful). Snails can cause feelings of disgust in children and young people. But if they observe them more closely and have contact with them, then curiosity and thirst for knowledge usually predominate. The pupils can discover astounding phenomena which they are able to examine themselves in simple experiments.

1. Factual information about snails Biology of land snails Snails (Gastropoda) make up the class of animals with the most species from the phylum molluscs (Mollusca). They can live on land as well as in the water (snails and shellfish). In the following, only the biology of the land snail is described. In land snails, oxygen intake occurs through a network of thin-walled blood vessels in the mantle cavity under the shell. Loss of water through breathing is a serious problem for snails that live on land. Protection against loss of water is provided by a particularly thick fold of skin in the mantle which closes off the mantle cavity. The stream of air which the snail breathes in passes through a small opening called the breathing pore or pneumostome. The snail can use its muscles to control the opening of the breathing pore. Breathing takes place by opening and closing the breathing pore as well as by raising and lowering the floor of the mantle cavity, which you can compare to the use of the diaphragm in vertebrates. Many snails make use of the cool and damp conditions at night and are nocturnal. If it is too dry, they look for a suitable hiding place to wait out the dry period. Some snails crawl up plant stems and fall into a state of dormancy. They then close off the entrance to the shell with a seal made of slime, with which they also stick themselves to the surface they have chosen. Because of their famously slow method of movement, the snail’s radius of activity is very small. The chance of meeting a partner for mating is rather low. Therefore androgyny is an advantage: they have double the chances of reproduction with a low number of individuals because the snail can reproduce with every member of the same species it meets, assuming they are ready to mate. In contrast to the sea snail, the development of the land snail takes place in a closed egg, from which a complete young snail hatches. A land snail’s field of vision is greatly improved by having eyes on a long pair of tentacles. The second pair of smaller tentacles serve above all as feelers.

Snails Snails usually have a spiral-shaped shell which is wound around a spindle. This is the snail shell which they retract their soft bodies into when there is danger. Because of this, they are asymmetrical, and this asymmetry is mirrored inside their bodies. The snail shell is always constructed in the same way. The direction of the spiral is typical for a particular species.  Snails

You can occasionally find snails with the spiral formed in the other direction, but these are very rare. These rare animals are called “snail kings”. By eating food rich in lime, the snail builds its shell which provides protection against predators. The shell provides extra protection against drying out and can be closed off with a slime or lime layer during dry periods.

Slugs We usually call all snail-like animals without shells that live on land slugs. After periods of rain we can often find the Portuguese slug, and many of its smaller relatives also live in our gardens. The gradual reduction of the shell can be observed in some families of snails. The family of glass snails (Vitrinidae) has a very thin shell, the walls of which look translucent. In the common slugs (Arionidae), all that is left of the shell of its ancestors is a few grains of lime. Not having a shell saves energy as the slug does not have to carry it around. Instead of a protective shell, slugs have very thick slime which protects them against drying out and had a disgusting taste which helps to protect against predators. The regional poet Hermann Loens described this vividly in his story “A disgusting animal” and he also did his own experiments on the subject.

Snail slime and snail’s pace Most native snails use their muscular foot to move themselves along on a trail of slime. From below you can observe the wavelike contractions of the foot muscle.

Fig. 2: The Great grey slug (Limax maximus) is a harmless waste recycler in the garden.

The snails’ crawling movement is one of the methods of moving which uses the most energy in the animal kingdom. Snails produce their own “road surface”, a gel which changes its physical charac­ teristics according to the situation: sometimes it is a glue, sometimes a lubricant. Because of the amount of energy necessary to move, some snails spend their whole lives in a radius of only a few metres from the place where they hatched. On the other hand, snails can reach a speed of up to 20 metres per hour, in particular when they are moving along another snail’s slime trail when they are looking for a mate.

The radula Like all molluscs, snails have a rasping tongue, the radula, as a mandible. This is full of horny teeth made of chitin and is used for scraping off particles of food from underneath. If you let a snail crawl over your hand, you can feel the rasping.

Fig. 3: Contracting waves as seen when a snail crawls over a piece of glass. The dark, moving stripes are visible. On the left of the picture you can see the characteristic slime trail that the snail leaves behind it.

Snails 

Senses Perception of light A Roman (or Burgundy) snail can see with the eyes on the ends of its two longer feelers. In the thickening at the end of the feelers you will find the snail’s eyes, but without a magnifying glass you can only see them as two black dots. This snail at least has eyes with lenses which are made of a formless, light refracting gelatinous mass in the ballshaped optic vesicle. The outer wall of the feelers consists of transparent cells and forms a protective corneal skin. There are also other cells around the snail’s body which can sense light. That is why a snail retreats into its shell when a shadow suddenly falls over it (in the wild this is a possible predator).

Fig. 4: The White lipped snail has two pairs of feelers on its head: the upper feelers have an eye and an organ for the sense of smell, and the lower feelers have an organ for the sense of touch. At the slightest disturbance they are retracted extremely quickly.

Sense of touch The whole body of the snail is sensitive to touch. This is especially true of the feelers or tentacles of the snail and the rest of the head. When the snail comes in contact with an obstacle, a retractor muscle retracts the part of the body that has been touched with lightning speed. In the case of vigorous stimulation, the whole snail can retreat into its shell by using a strong muscle attached to the centre of the shell.

Sense of smell and taste Snails can sense sources of food at considerable distances (up to several metres) and move purposefully towards them. A snail will crawl towards a lettuce leaf because it can smell the leaf from a distance. But when the lettuce has been treated with a foul-tasting chemical, for example acetic acid, as an experiment, the snail turns away after the first contact and literally starts to foam – a method of protection against contact with unpleasant substances. Perception of temperature and moisture The perception of temperature and humidity is essential to survival for snails. They make use of cooler temperatures in the relatively damp evening air, and during the day when the air is hot and dry they look for a hiding place to rest in. In general, our most common snails prefer cooler, shady areas rather than places where the sun is shining. This can be observed in any garden where snails purposefully move towards areas which have just been watered. Sense of hearing This is the only sense which snails do not have.

Way of life Snails are, with only a few exceptions, plant eaters. In contrast to the opinion of most people, a large number of snails do not feed on fresh green plants but prefer decomposing plant material. Some snails even love eating moulds. Snails eat an impressive amount of plant material in relation to their body mass: a fully grown Roman (Burgundy) snail eats up to 6 grams of plant material per day.

 Snails

In autumn the Roman snails bury themselves in an area protected from the wind and covered with vegetation. They dig a hole with their foot and spend the winter there. This winter hole is closed off from the inside with earth. After that, the snail produces a secretion containing lime which becomes a hard covering when it comes in contact with the air. This is called the epiphragm and solidifies to close off the opening to the shell. Now the snail can survive frosty winter temperatures.

Importance in the ecosystem Snails play an important role in shredding and transforming organic substances. They combine their slime with particles from the ground and improve the structure of the soil. Many snail species are specialised in feeding on unusual materials or those difficult to digest and so they contribute to the decomposition and transformation of these substances. Because of their high biomass, snails are on the other hand an important source of food for other animals. They are a source of food for birds, hedgehogs, moles, amphibians, reptiles, ground beetles and countless spider species. In central Europe, the very common banded wood snail is an important source of food for thrush species, which crack the snail shell using stones on hard ground. Some snail species are predatory themselves. Roman (Burgundy) snails eat the eggs of other snail species. From the human’s point of view, only a few snail species are harmful to crops and garden plants. The most unpopular and most common one is the introduced Portuguese slug (Arion lusitanicus) because of its high rate of reproduction. The garden slug (Arion hortensis) is also unpopular, as are several other slug species of the genus Deroceras.

Fig. 5: The Red slug (Arion rufus) used to be common but has decreased dramatically and is now endangered over the whole country.

Endangered species Public interest is concentrated on the snails which are considered to be harmful. It is easy to overlook the fact that non-selective use of snail bait affects all species of snails. Therefore many harmless species such as the waste recyclers and the attractive tiger slug are also affected, as are countless species which prey on snails, for example, thrushes, hedgehogs, ground beetles etc., because their source of food is reduced in our gardens. As well as that, snails, together with aphids, make up the greatest animal biomass in our gardens. Killing off snails removes a significant basic food resource in a food web and has direct consequences for many predators. Many people are not aware of this aspect when they lay out snail bait. 60 % of all snail species in Bavaria are already endangered – that means more than half the native molluscs. This figure is considerably higher than in birds (47 %) and mammals (49 %) and shows the dramatic situation among Bavaria’s snail fauna. It is particularly worrying that species which used to be common, such as the red slug (Arion rufus) and many other “non-target species” of snail removal, are now on the Red List of endangered species in Bavaria (Bavarian

Fig. 6: The Marsh whorl snail (Vertigo antivertigo) is an endangered species in Bavaria.

Snails 

State Office for Environmental Protection 2003). So there is a danger that, in the long term, a significant proportion of Bavaria’s snail fauna will die out.

Literature Identification books Pfleger, V. (1984): Snails and seashells of Europe. Land and freshwater species. (Schnecken und Muscheln Europas. Land- und Süßwasserarten). Kosmos Verlag, Stuttgart This guide to the more common snails and seashells is easy to understand and has good illustrations. However, it is now only to be found in second-hand bookshops. Gloer, P. u. C. Meier-Brook (2003): Freshwater molluscs. An identification guide for the Federal Republic of Germany. (Süßwassermollusken. Ein Bestimmungsschluessel fuer die Bundesrepublik Deutschland). Deutscher Jugendbund fuer Naturbeobachtung, 13th edition, Hamburg Hausser, J. (2005): Identification Guide for Gastropods in Switzerland. (Bestimmungsschlüssel der Gastropoden der Schweiz). Fauna Helvetica 10, Neuchatel. These are good identification guides for native snail fauna.

Teaching materials Buholzer, T. (2002): The Life of Snails. (Schneckenleben). Patmos Verlag, Düsseldorf This has good photos and the text is easy to understand. For years 1-6. Naber, A., Latorre, S. (2001): The Creative Book “Snails”. (Das kreative Sachbuch „Schnecke“). Als Verlag, Dietzenbach Suitable for years 1-4. Covers every aspect of the topic of snails. Wieringer, S., Zindler, K. (2006): The Snail Workshop. (Die Schnecken-Werkstatt). Verlag an der Ruhr, Muehlheim a.d. Ruhr Suitable for years 1-6. Loose leaf copies. Ideas for an interdisciplinary approach (English, German, Maths). Suitable for organising a project day at school. Snails. (Schnecken) FWU-Nr. 4602440, DVD, 31 mins, 2007. From the „Löwenzahn“ series: Peter’s Snail Race. (Löwenzahn: Peters Schnecken rennen) FWU-Nr. 4231594, VHS, 25 mins, 2003/1999. The Roman/Burgundy Snail. (Die Weinbergschnecke) FWU-Nr. 4201671, VHS, 11 mins, 1993/1987. Nature in the Garden – The “Naked” Truth. (Natur im Garten – Die „nackte” Wahrheit) DVD, 63 min, 2002. Universum Film. Co-production by ORF, epo-film and the LW-Werbe- und Verlagsgesellschaft. An unbelievably humorous film about the everyday conflict between garden owners and snails in the garden. With Erwin Steinhauer and Alfred Dorfer.

Internet addresses www.eduvinet.de/mallig/bio/7shnek/7snekM1.htm Position and function of the inner organs, from junior high level. www.rz.uni-frankfurt.de/~hlehnert/schnecke/allgem.htm Nice identification guide, from year 2. www.weichtiere.at Comprehensive information, nice photos. For junior and senior high school as well as for teachers to use for research

6 Snails

www.affenterz.de/loewenzahn/thema/ausgabe26/page1.asp Informative website from the series “Löwenzahn”. Can be used from primary school upwards. www.kidsnet.at/Sachunterricht/schnecke.swf Quiz for children from year 2.

2. Legal information and handling of snails For the purposes of education, all large snails are allowed to be used for the activities described if they are kept in a humane method. The only exception is the Roman (Burgundy) snail (Helix pomatia) which is specially protected according to the Federal Species Conservation Act. It falls under the bans concerning species protection according to Article 44, Paragraph 1 of the Federal Nature Conservation Law (BNatSchG). According to this law, it is forbidden, among other things, to take Roman (Burgundy) snails away from the wild. However, in Article 3 of the Species Protection Legal Exemptions, the following is allowed for purposes of education: “Teachers at state or private educational institutions accor­ ding to Article 3 of the Bavarian Law for Childcare and Education, teaching staff of pre-school and childcare institutions, according to Article 2 of the Bavarian Law for Children’s Care and Education, as well as staff of other environmental education institutions are allowed to use specially protected animal and plant species in their lessons in areas such as ponds and gardens which have been created for education and training purposes. This is according to Article 10, Paragraph 2 No. 10 BNatSchG”. They are only allowed to take as many animals as are absolutely necessary, and after the activity the animals are to be let go again at the same place from which they were taken. In all other cases, you must apply for an exemption from the bans in Article 42 Paragraph 1 of the Conservation Law (BNatSchG) from the Upper Conservation Authority at the corresponding government offices. You can find a sample application in Appendix B at the end of the whole publication. The governments and their addresses are listed in Appendix C at the end of the whole publication. Never pull a snail off a smooth surface (you You must carry this exemption with you when you are taking the animals. could damage its retractor muscle). Pick up it by its shell and carefully pull it sideways from The hints for keeping the animals appropriately the ground. and their careful handling must also be kept to when looking after snails. You must discuss this with your pupils before the activity. Before every activity, point out the rules in the box on the right. Hint: If a snail has retreated into its shell, the teacher can encourage it to come out by placing it in warm water (c.30deg C). The snail will not drown. Depending on the species it can survive for over 12 hours under water. Please do not experiment with this! For reasons of hygiene, you should wash your hands after every activity. Larger snails like, for example, banded snails and Roman (Burgundy) snails have the advantage that you can pick them up by their shells and do not get slimy fingers.

Snails 7

3. Activities

Fundamental aims of the activities • To discover diversity among native snails • To reduce prejudices and feelings of disgust • To recognise the role and usefulness of snails in an ecosystem • To awaken interest in snails as examples of molluscs

Activities A 1 Discover diversity among snails Knowledge of species A 2 Building a snail terrarium Keeping snails temporarily, habitat, accepting responsibility for an animal A 3 Measuring, weighing and drawing snails Examine the body structure of a mollusc A 4 A snail’s movement Sequence of movements, speed A 5 Snail slime Recognise the function of snail slime A 6 A snail’s senses Reaction to light, touch, chemical stimulation A 7 Observe a snail’s food intake A 8 Diversity among snail shells Variation within a species as a key principle of evolution

Additional material A 1_1 Identification handout Snails I A 1_2 Identification handout Snails II A 1_3 Identification handout Slugs A 1_4 Identification handout Water snails A 1_5 Identification handout Molluscs A 3_1 Outer features of snails and slugs

Activity 1

Discover diversity among snails

Season:

Factual background to the activity

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

Most pupils whose parents have their own garden will know about the problem of the “plague of snails” in the vegetable garden. Of the 500 snail species in Bavaria, only a few of them cause damage by eating crop and garden plants. Most snails are (from the point of view of the gardener) harmless or they are even compost recyclers and are an advantage because they improve the soil. The problems are caused by species that reproduce heavily, especially the Portuguese slug (Arion lustianicus). With the negative image of snails as a background, the snail collecting activity receives special meaning. When collecting, the astounding diversity among snails will become clear. When you discuss the results of the collection together afterwards, it is a good opportunity to mention the importance of snails in the ecosys­ tem and also to talk about the topic of the fight against snails. You can find reasons for and against fighting snails and discuss them with your pupils. Reasons for the fight against snails: • the Portuguese slug has too few predators to prevent large scale reproduction • plants which are in danger from snails can barely survive without our help • the iron compounds you can get today to fight snails are relatively compatible with nature and are biodegradable

Grade level:

PS

JHS

Development:

SHS

Aims of the activity • To be able to identify native snail species with the help of illustrations

Materials • Container for collection • Gloves for particularly sensitive children; you can also use a large leaf to touch slugs if necessary • Additional Materials A1_1 to A1_3 Identification handouts Snails and slugs • Also the Additional Materials A1_4 to A1_5 Identification handouts Water snails and Molluscs if there is a pond or other body of water. Several kitchen sieves or large-meshed nets are useful for searching round the edges of the water • Magnifying glass (10x) for looking at very small snails • Observation report

• the plants that are in danger are effectively protected for a particular amount of time Reasons against the fight against snails: • snail poisons like “snail bait” only fight the symptoms; the actual causes of the snail plague (for example, not enough predators, growing of plants that snails love, too much fertiliser) are not solved • the use of snail bait must be repeated continually and is expensive in the long run • sometimes passive measures are enough, like building a fence against the snails or collecting them up to protect plants that are in danger and to avoid the use of poisons • you can choose plants for your garden which snails do not like (for example St. John’s wort, yellow chamomile or marigolds)

Snails – A 1_1

Activity 1

• using poisons against snails does not differentiate between the problematic snail species and the species which are not a problem and which make up the majority of the snails; it also affects the Roman (Burgundy) snail and the Great grey slug which are harmless recyclers • snails are an important food source for many other animals (for example, blackbirds, thrushes, hedgehogs, ground beetles); removing snails indirectly affects other useful animals • snails are part of our biological diversity and many species are endangered nowadays.

Implementation • places with large numbers of snails are shady and semi-shady areas of the garden with various assorted plants as well as the edges of paths and wooded areas with lots of hiding places (piles of leaves, pieces of wood, flat stones etc); the chances of finding snails can be greatly increased by putting boards directly on the damp ground in the morning. • turn over all loose items on the ground (fallen leaves, wood and bark pieces, flat stones), and also look in small holes, cracks and around clumps of moss. • time of day: snails are most active and you can make the largest col­ lection on days when the ground is wet (after rain) or in the early morning hours. • look in small bodies of water for snails and other shells. • collection: the brown Portuguese slug is the most common; so that the pupils do not collect too many of the same species, tell them to take only one example of each type of snail. • identify the snails you have found as best you are able • write down the number of each species you have found For the following activities you can keep using the larger snails in a suitable container (for example a large jam jar with holes in the lid which has damp grass and leaves inside). Alternatively the pupils can collect larger snails themselves as homework.

Snails – A 1_1

Activity 2

Building a snail terrarium

Season:

Implementation

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

• Place a layer of garden soil, stones, leaves, moss orsimilar items in the bottom of the aquarium. Sandy, dry soil is not suitable.

Grade level:

• Place some thicker sticks in the aquarium for “climbing” on.

PS

JHS

Development:

SHS

• You must always keep the snail terrarium damp. Use a spray bottle to help, but avoid a build-up of water.

Aims of the activity

• It is best to use mosquito netting with Velcro strips to keep the snail terrarium completely closed.

• To practise handling living animals responsibly

• The snails should always have food on offer such as lettuce, dandelion leaves or young vegetable plants. Remove old and wilted leaves regularly. • As well, the snails need lime. It is best to use cuttlefish, egg shells, pieces of chalk or distribute food containing lime in the terrarium. If the snails do not get enough lime they will suffer from brittle shells among other things.

• To build a snail terrarium for observing snails

Materials • An aquarium (alternatively a large, transparent plastic container • Garden soil • Pebbles, stones • Moss, leaves

• Put the snail terrarium in a cool place without direct sunshine.

• Mosquito net with Velcro strips (cover for the terrarium)

Opportunities for observation • Way of feeding and the food they prefer

• Sticks for climbing

• Way of moving

• Food: lettuce, dandelion leaves, young vegetable plants

• Amount of activity depending on the time of day • Places the snails retreat to

• Spray bottle with water

• Additional Materials A 3_1 Outer features of snails and slugs • If you keep them for a longer time: lime (cuttlefish, which can be bought for example at pet shops, cooked egg shells, white chalk of food containing lime for small animals)

Snails – A 2_1

Activity 3

Measuring, weighing and drawing snails Implementation Measuring • Measure a snail (length, width, height of the shell) and write down the results in an observation report. Weighing • Weigh the snail and write down the weight Drawing • Examine the snail in detail with a magnifying glass (skin, feelers, eyes, breathing hole) • Draw the snail (depending on the class level this will vary in accuracy, for example at primary school level concentrate on the main points: foot, shell, feelers. At secondary school level you can place more importance on and exact drawing and details.

Season: Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

Grade level:

PS

JHS

Development:

SHS

Aims of the activity • To practise methods of drawing, measuring, observing and keeping a report

Materials • Snails • Ruler • Letter scales, kitchen scales, diet scales or similar • Magnifying glass (10 x magnification) • Pencils for drawing (alternatively a camera) • Observation report • Additional Materials A 3_1 Outer features of snails and slugs

Snails – A 3_1

Activity 4

A snail’s movement

Season:

Implementation

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

a) Observe a snail’s movement • Put a snail on a sheet of glass.

Grade level:

• Put the sheet of glass on wooden blocks or on matchboxes (approximately 5 cm high).

PS

JHS

Development:

SHS

• Put a mirror underneath. • In the mirror you can see the snail’s foot from underneath when it is moving. • Alternatively you can lift up the sheet of glass and observe directly from underneath. b) Calculating a snail’s pace • Put a snail on a sheet of glass and mark the starting point with a marking pen. • Measure the time; let the snail crawl for a minute. • First of all, draw the path the snail has taken with a marking pen. • Then lay a piece of wool or string on the path you have drawn. • Measure the length of the string with a ruler; the result is the number of centimetres travelled in a minute • Depending on the class level: calculate the speed in km/h, metres per day or similar

Aims of the activity • To observe a snail’s way of moving • To determine the speed of the movement

Materials • Sheet of glass • Wooden blocks or matchboxes to hold the sheet of glass up • Mirror • Ruler • Marking pen • Wool or parcel string • Stopwatch

Sheet of glass

Mirror

Snails – A 4_1

Activity 5

Snail slime

Season:

Factual information

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

The production of slime changes to suit the particular ground. The animal glides along on the slime like on a cushion. This even works on a sharp blade. On Rough surfaces the slime trail is noticeably thicker than on a smooth surface. Snails can even crawl over a kitchen grater without hurting themselves.

Grade level:

PS

JHS

Development:

SHS

Implementation

Aims of the activity

Preparation by the teacher:

• To observe the movement of snails and the protective effect of snail slime

• cut the cork in half lengthways

Materials • break the razor blade in half (be careful, it is very sharp!)

• cut the cork half lengthways along the top and push one half of the razor blade into the cut (sharp side upwards)

• White or Brown-lipped snails. Only use Roman (Burgundy) snails for experiments without sharp blades because this species can injure itself more easily. • Sharp knife which has been placed with the blade upwards in a piece of wood. Alternatively (because it is more spectacular) use razor blades which have been attached to wine corks (see the illustration). • Food to attract the snails • Adhesive tape • Kitchen grater, alternatively sandpaper as well as a smooth sheet of glass

Experiment 1 • Put the blade in front of the snail and attract the snail with food, so that it crawls by itself over the blade.

Perform sampling only under a teacher‘s super­vision

• You must not touch the snail while it is sitting on the razor blade! • To make it more stable, you can fix the cork to the surface (with pins, glue, adhesive tape or similar) Experiment 2 • Put the snail on various surfaces (kitchen grater/ sandpaper, sheet of glass), then compare the slime trail and discuss.

Snails – A 5_1

Activity 6

A snail’s senses

Season:

Factual information

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

Snails can perceive nearby movements because of their ability to detect light. They mostly stop crawling then and begin to retract their feelers and then their head. If a shadow falls on them very quickly, a reflex causes them to retreat into their shell. This biological sense of the so-called shadow reflex is a reaction to a possible attack by predators.

Grade level:

PS

JHS

Development:

SHS

Aims of the activity

The whole skin of the snail is sensitive to touch. In the case of strong or repeated stimulation the snail will retreat into its shell.

• To examine a snail’s senses

It is difficult and not really possible to completely separate the sense of smell and sense of taste in snails. Therefore you can describe those senses collectively as a chemical one. The feelers, the lips and the edge of the foot above all are sensitive to chemicals, the foot particularly at the front edge. In the case of very unpleasant substances like vinegar you can observe a foaming used as a protective mechanism.

• For the upper classes: to independently plan experiments concerning a snail’s senses, to carry them out and evaluate the results (Additional materials A 6_1 and A 6_2

• To document and evaluate results

Materials

Implementation

Experiment 1: Perception of light • Flashlight (not a LED lamp, because the light is too bright)

Experiment 1 – Perception of light • Put the snail on damp paper.

Experiment 2: Sense of touch/being touched • Glass rod or blunt pencil

• At the beginning, the snail must be crawling with its feelers fully extended (and the observers must be as quiet as possible!).

Experiment 3: Sense of smell/taste • Sugar water, water with artificial sweetener

• In normal daylight quickly make a shadow over the snail with your hand. The shadow reflex causes the eyes on the feelers to retract and often the whole snail retreats into its shell.

• Samples of food (lettuce leaves, dandelion leaves, pieces of fruit, …)

• Then wait until the snail is crawling again or experiment with another crawling snail.

• Vinegar, lemon juice, perfume or other strongly smelling liquids

• Cotton buds

• Shine a flashlight onto various parts of the snail’s body.

Experiment 4: Sense of temperature • Two glasses (volume of approx. 0.2L), one filled with cold water (c. 15deg C) and the second filled with warm water (c. 40deg C)

• Observe and write down the snail’s reaction.

• Plastic ruler

• Make conclusions about the position of the organs of light perception: the eyes are on the ends of the feelers, further cells which perceive light are distributed over the whole body. These have a protective function against predators.

Experiment 5: Sense of position • Straw or wooden stick, 1 cm diameter • Two piles of books

Experiment 2 – Sense of touch/being touched • Carefully touch the snail on different parts of its body with a glass rod or blunt pencil. • Observe and write down the snail’s reaction. • Make conclusions about the position of the organs of touch: they are mostly situated in the head region but you can find areas that react to being touched along the whole foot. The part that you have touched usually retracts quickly. This is also a protective function against predators.

Snails – A 6_1

Activity 6

Experiment 3a) Sense of taste: Sense of taste when looking for food • In den Weg einer kriechenden Schnecke einen Tropfen Zuckerwasser träufeln. Sobald sie mit der Sohle den Tropfenrand berührt, hält sie an und saugt das Zuckerwasser ein. Ein entsprechender Tropfen mit künstlichem Süßstoff wird abgelehnt. • Put a drop of sugar water in the path of a crawling snail. As soon as its foot touches the edge of the drop it stops and begins to suck up the sugar water. Another drop of water sweetened with artificial sweetener is rejected. • Place several sample of food at a greater distance (approx. 30 cm) from the snail. • Observe and write down the snail’s reaction. • Make conclusions about snails’ sense of smell”: The sense of smell is strong, the organs of the sense of smell are mostly in the head area, and snails move purposefully towards a source of food.

Experiment 3 b) Reaction to unpleasant substances • Dip a cotton bud in vinegar and draw a line with this directly in front of the snail. • Alternatively you can draw a circle of scent around the snail. • Observe and write down the snail’s reaction.

Fig. 7: The foaming of this Roman (Burgundy) snail is a protective reaction against unpleasant substances and can also be used against predators.

• Make conclusions about snails’ sense of smell: Snails have a strong sense of smell, the organs of the sense of smell are mostly in the head area, and snails avoid the smells of substances that they find unpleasant.

Experiment 4: Sense of temperature • Fill two glasses to the top with water of different temperature (10 °C, 40 °C) and put a plastic ruler over the top. • Put the snail on the ruler in the middle between the two glasses.

10 °C

40 °C

• Observe and write down the snail’s reaction. • Make conclusions about snails’ sense of temperature: snails avoid high temperatures, as protection against drying out they prefer a cool environment.

Schnecken – A 6_2

Activity 6

Experiment 5: Sense of position • Wedge a straw, wooden stick, thin twig or similar between two piles of books

• Put a snail on the straw. • Observe and write down the way the snail moves. • Change the position of the snail (put the front upwards, downwards, turn it on its head etc). • Observe and write down the snail’s reaction. • Make conclusions about snails’ sense of position: For this balancing act the snail must be able to recognise the position it is in.

Snails – A 6_3

Activity 7

Observe a snail’s food intake

Season:

Implementation

Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

• Put a snail on a sheet of glass and offer it various samples of food.

Grade level:

• Observe the snail’s reaction and describe the preferred type of food: snails mostly feed on plants but not exclusively. • Observe the snail from underneath the sheet of glass when it is feeding: you can see its rasping tongue (radula). • Make a feeding mixture from flour and water and put some on your finger. Feed the snail with this: you can also feel the radula working.

PS

JHS

Development:

SHS

Aims of the activity • To observe snails when feeding • To recognise the function of the radula • To determine the preferred type of food of snails

Materials • Sheet of glass or Perspex about the size of an A5 sheet of paper; put adhesive tape on any sharp edges • Snails • Samples of food: dandelion, lettuce leaves, fee­ ding mixture (made of flour and water), pieces of fruit, sausage, cheese, pieces of bread, pie­ ces of cucumber

Snails – A 7_1

Activity 8

Diversity among snail shells

Season: Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug

Grade level:

PS

JHS

Development:

SHS

Aims of the activity • To discover diversity of colour and pattern in snail shells • To recognise the importance of this diversity Fig. 8: There is an enormous diversity among the Shells of the Brown lipped-snail (Cepaea nemoralis). This also applies to the White-lipped snail (Cepaea hortensis) which is not pictured.

Materials • Empty shells of the common banded snails (especially the banded wood snail and the white lipped banded snail). Check carefully that the shells really are empty!

The mysterious diversity among lipped snails demonstrates a key principle of evolution – diversity within a species. The Brown-lipped • Notebook and pencil snails and the white-lipped snails are a supreme example of this principle. They are among the most diverse snails anyway. The difference between these two lipped-snail species can be determined by the dark band (lip) at the edge of the shell which is always present in the banded wood snail but never in the white-lipped snail. The more common species is the species with the black lip. The extreme diversity of colour which can be observed in both species depends on natural selection by predators and also other environmental factors. This phenomenon is based on a genetic process (called polymorphism). Thrushes are the main enemy of lipped snails. Thrushes can find non-lipped snails more easily in the thick plant growth of a meadow. Having bands (lips) is in this case an advantage which allows better camouflage. The banding also has a disadvantage: a dark shell absorbs heat radiation, a light yellow or pink shell reflects heat better. The colour of the shell therefore influences the temperature of the snail inside it. For this reason, lipped snails with dark banding can be more often found in forests and other shady places.

Implementation • This can be carried out at any time during the year when there is no snow on the ground. • Collect snail shells together with the pupils. You can find lots of empty snail shells in semi-shady areas among and under wood in gardens that are close to a natural state, and around the edges of forests and fields and wetlands. Alternatively ask the pupils to collect snail shells as part of their homework. • For pupils from junior high level onwards, the connection with the habitat is also interesting. Possible question: how many non-lipped, lightly lipped and strongly (darkly) lipped shells come from which habitat? Discuss with the pupils what reasons diversity in shells of

Snails – A 8_1

Activity 8

the same species could have. Dark shells are mostly found on shady, dark ground under wood or in the forest. Light-coloured shells (yellow to pink coloured) are mostly found in warmer, open areas where there are lots of hiding places. • Display all the shells that have been collected, sorted according to colour and pattern.

Snails – A 8_2

Additional Material A 1_1

Snails I

White-lipped snail Brown-lipped snail

Burgundy snail

14 – 20 mm (rarely up to 22 mm)

18 – 25 mm (rarely up to 30 mm)

3 – 5 cm

Perforatella incarnatus

Fruticicola fruticum

13 – 16 mm

13 – 23 mm

Eastern heath snail

Western heath snail

14 – 20 mm

9 – 25 mm

Wide mouthed glass snail

Mask snail 7 – 11 mm

8 – 11 mm

Lapidary snail

Copse snail

12 – 20 mm

14 – 28 mm

Cheese snail

Cellar snail

11 – 15 mm

9 – 12 mm

Black gloss snail

Amber snail

6 – 7 mm

6 – 8 mm

Mountain Bulin Snail

Ear-shaped glass snail

6 – 7 mm

6 – 7 mm

Pelucid glass snail

5 – 7 mm

4,5 – 6 mm

To examine small snails better some are shown bigger shortest – longest observed animals (size of the shell) Attention: For species with tower-shaped shells the height information can be found on the backsite of this sheet

Garden disc snail

Hairy Snail

Petasina unidentata

5 – 12 mm

5 – 8 mm

Snails – Additional Materal A 1_1

Additional Material A 1_1

Further information about the snails illustrated in Identification handout Snails I Species Roman (Burgundy) snail Helix pomatia Brown-lipped snail Cepaea nemoralis White-lipped snail Cepaea hortensis Copse snail Arianta arbustorum Fruticicola fruticum Perforatella incarnatus or Monachoides incarnatus Lapidary snail Helicigona lapicida Cheese snail Helicodonta obvoluta Eastern heath snail Xerolenta obvia Western heath snail Helicella itala Cellar snail Oxychilus cellarius Wide mouthed glass snail Aegopinella nitens Mask snail Isognomostoma isognomostomos Amber snail Succinea putris Black gloss snail Zonitoides nitidus Mountain bulin snail Ena montana

Hxw Identifying features (c. in mm) 30 - 50 x 30 - 50 Largest snail 10 - 17 x 18 - 25 Spherical, slightly depressed shell; 2 main colours and (rarely - 30) 5 dark bands (lips) in various combinations, can blend into one another; edge mostly dark brown 12 - 22 Spherical, slightly depressed shell; 2 main colours and (rarely - 30) 5 dark bands (lips) in various combinations, can blend x 14 - 20 into one another; edge of the opening mostly white (rarely - 22) 10 - 22 x 14 - 28 Spherical shell with yellow-brown spots and usually 1 dark brown band on the outside of the spiral 10 - 19 x 13 - 23 2 main colours, pale yellow and reddish brown, in both variations a brown band on the edge of the spirals is possible 9 - 11 x 13 - 16 Shell with characteristic structure (tapered rods on both sides – magnifying glass); edge of the opening is red 7 - 9 x 12 - 20

Flattened shell with a strong keel, with grainy structure (magnifying glass)

5 - 7 x 11 - 15

Flat and tightly wound, brown shell

5 - 12 x 14 - 20 Strongly flattened shell, the spiral is hardly raised; shell colour is chalky white with dark brown or nearly black bands 5 - 12 x 9 - 25 Strongly flattened shell, the spiral is hardly raised; shell colour is white to pale yellow, mostly with pale brown bands ~ 6 x 9 - 12 Light brown, translucent, flat shell

Habitat

Way of living

Sparse forest, hedges, bushes, Likes lime, can get tall herbaceous vegetation fairly old, sometimes over 20 years Fairly wide range of biotopes Mostly higher up in trees, (including forest, bushes, hed­ bushes etc ges, tall herbaceous vegetation Fairly wide range of biotopes Mostly higher up in trees, (including forest, bushes, hed­ bushes etc ges, tall herbaceous vegetation Wide range of biotopes, in forests and open areas. Forests, hedges, bushes, tall herbaceous vegetation, reeds Mostly in forest biotopes, hedges and bushes Rock and wall biotopes, areas of old trees in structure-rich forest or hedges Forests and hedges

In plants and trees

RL BY -

-

Prefers warm, humid climate; sensitive to dry periods Adult animals are mostly on the ground, young also in vegetation Mostly hiding in cracks and V crevices In leaf litter and deadwood; likes lime Likes lime

Open, dry biotope (dry grassy areas, embankments, areas of waste ground) Open, wet-dry to dry biotope Likes lime

-

Moderately damp areas, also deciduous forest

Lives in the leaf litter

-

Lives in the leaf litter

-

5 - 7 x 8 - 11

Greeny-brown, translucent shell with slightly raised spiral and very much wider last coil

Moderately damp to damp areas, including forests

4 - 7 x 7 - 11

Depressed spherical shell with characteristic chalky protrusions (“teeth”) which project into the opening

In structure-rich forests of the Mostly under deadwood, montane level in leaf litter or scree

-

10 - 17 x 6 - 8

Thin, translucent light – mid brown shell with rapidly expanding whorls

Various damp and wet biotopes

Climbs up vegetation

-

Wide range of damp to wet biotopes

In the leaf litter

-

Structure-rich, damp deci­ duous forest (and wetland forest)

Mostly on tree trunks or on low-growing plants. The young animals are camouflaged in soil and leaf litter. Lives in the leaf litter

-

Lives in the leaf litter

-

Lives on the ground

-

In the leaf litter or on lowgrowing plants

-

In the leaf litter or on lowgrowing plants as well as under deadwood

3

3-4 x6-7

Glossy shell with slightly raised spiral. The dark grey to black soft part of the body makes the living animals look nearly black. 1,5 -< 2 x 6 - 7 Conical, very solid shell

Ear-shaped 2,5 - 3 x 6 - 7 glass snail Eucobresia diaphana Pellucid 3,5 - 5 x 4,5 - 6 glass snail Vitrina pellucida Garden disk snail ~2x5-7 Discus rotundatus

Thin, transparent, strongly reduced ear-shaped shell

(Common) Hairy snail Trochulus hispidus Petasina unidentata

5 - 6 x 5 - 12

Depressed shell with flatly conical to slightly raised spiral. The young animals have thick, short hairs.

4-6x5-8

Spherical conical formed shell, mostly with chalky horns In vegetation in damp forests, (“teeth”) at the opening. Young animals have thick hairs, the also in mountain regions adult often have gaps in the hairs or they are worn away.

Thin, transparent, spherical, strongly reduced shell, into which the animals cannot fully retract itself Disk shaped, ribbed shell, brown with red spotted pattern

Explanations: ~ = approximately.; =< = scant; => = abundant, at least Endangered species: RL BY (= Red List Bavaria): 3 = endangered; V = warning stage

Snails – Additional Materal A 1_1

Moderately damp to damp areas (forest, tall herbaceous vegetation, reeds) Various moderately damp areas (including forests, fields) Various, mostly moderately damp to damp biotopes (in­ cluding forests, hedges etc) Mostly moderately damp biotope, also in crop areas

-

Additional Material A 1_2

Snails II

Plaited door snail

Thames door snail

c. 4 mm

3,5 – 4 mm

Clausilia rugosa parvula

Rayed glass snail 3,5 – 4 mm

c. 2 mm

Chrystal snail

Brown hive snail

Glossy pillar snail

Ribbed Vallonia snail

Lovely Vallonia snail

3 – 4 mm

2,5 – 3,5 mm

2,5 – 3 mm

2 – 3 mm

2 – 3 mm

Moss snail c. 2 mm

Toothless column snail c. 1,5 mm

Cylindrical whorl snail c. 1 mm

Narrowmouthed whorl snail about 1 mm

Marsh whorl snail

Crested vertigo snail

Short-toothed herald snail

Slender herald snail

about 1 mm

c. 1 mm

c. 1 mm

about 1 mm

To examine small snails better some are shown bigger shortest – longest observed animals (size of the shell) Attention: For species with tower-shaped shells the height information can be found on the backsite of this sheet

Prickly snail

Smooth coil snail

c. 2 mm

1 – 1,5 mm

Snails – Additional Materal A 1_2

Additional Material A 1_2

Further information about the snails illustrated in Identification handout Snails II Species

Hxw (c. in mm) ~ 15 x ~ 4

Identifying features

Habitat

Way of living

~ 2 x 3,5 - 4

Covered with fine radial lines, glossy shell

Various moderately damp to damp places

Lives in the leaf litter

-

2 - 2,5 x 3 - 4

Thick, disk-shaped, tightly coiled shell with slightly raised spiral; transparent

Various biotopes, especially damp ones

Lives in the leaf litter

-

Depressed conical shell, finely striped on the upper side; Forests because of this silkily shiny Smooth, long egg-shaped shell Moderately damp to damp places, including fields, wetlands, tall herbaceous vegetation, forests Disk-shaped shell with (in fresh condition) sharp, very Exposed open places; also in regularly arranged ribs sparse, warm forests

Lives in the leaf litter, doesn’t mind acid conditions Lives in the leaf litter

-

In the leaf litter and in loose soil

-

Disk-shaped, mostly smooth shell; freshly glossy and transparent

In the leaf litter and in loose soil

-

Lives on the ground

3

Moderately damp to damp places, including wetlands, tall herbaceous vegetation, forest Sunny places with poor ground

In the leaf litter and on low-growing plants

V

Likes lime, xerophile (can live without much water)

V

Damp to wet open places

3

Wet open areas, especially near bodies of water

Lives in the leaf litter, does not climb vegetation much In the leaf litter and on the lower leaves of plants

varying amounts of dampness

In the leaf litter and on the lower leaves of plants

V

Wet biotopes

Lives in the leaf litter

V

Slim, conical shell

Varied biotopes

Lives in the leaf litter

-

Conical, compact shell with characteristic pointed, drawn out, lamellar ribs

Forests, hedges, bushes

Lives in the leaf litter

V

Fine, regularly striped, flat shell

Varied biotopes, generally with moderate dampness

Mostly lives in the leaf litter

-

Plaited Slim, glossy shell shaped like a high tower door snail Cochlodina laminata Thames 15 - 20 x 3,5 - 4 Shell with sharp ribs, shaped like a high tower door snail Balea biplicata Clausilia rugosa =< 10 x ~ 2 Slim, almost smooth shell, shaped like a high tower parvula Rayed glass snail Nesovitrea hammonis Crystal snail Vitrea crystallina

Brown hive snail 2 - 3 x 2,5 - 3,5 Euconulus fulvus Glossy 5 - 8 x 2,5 - 3 pillar snail Cochlicopa lubrica Ribbed ~1x2-3 Vallonia snail Vallonia costata Lovely ~1x2-3 Vallonia snail Vallonia pulchella Moss snail 3-4x~2 Pupilla muscorum Toothless 2,5 - 3 x ~ 1,5 column snail Columella edentula Cylindrical ~2x~1 whorl snail Truncatellina cylindrica Narrow-mouthed =< 2 x =< 1 whorl snail Vertigo angustior Marsh ~ 2 x => 1 whorl snail Vertigo antivertigo Crested ~2x~1 vertigo snail Vertigo pygmaea Short-toothed ~2x~1 herald snail Carychium minimum Slender ~ 2 x =< 1 herald snail Carychium tridentatum Prickly ~2x~2 snail Acanthinula aculeata Smooth coil snail =< 1 x 1 - 1,5 Punctum pygmaeum

Cylindrical egg-shaped solid shell, mostly with black chalky elevations in the opening (“teeth”) Conically cylindrical shell Slim cylindrical shell with regular, fine ribs.

Spindle-shaped, narrowly striped shell wound to the left; 5-6 teeth (magnifying glass), one of which is dis­ tinctive at the outer side of the opening Compact, egg-shaped, shiny shell with characteristic chalky elevations in the opening (6-10 “teeth”, magnifying glass), shell wound to the right Cylindrical egg-shaped, irregularly striped shell with characteristic chalky elevations in the opening (4-7 “teeth”, magnifying glass), shell wound to the right Spindle-shaped, glossy transparent shell

Explanations: ~ = approximately.; =< = scant; => = abundant, at least Endangered species: RL BY (= Red List Bavaria): 3 = endangered; V = warning stage

Snails – Additional Materal A 1_2

RL BY Forests, hedges and bushes In damp conditions several metres up tree trunks. Feeds on algae and lichens Various, mostly moderately In the leaf litter and on damp to damp biotopes low-growing plants as well as on trees, walls etc Mostly moderately damp rock Feeds on algae and lichens biotopes, forests, open areas; also walls and hedges

Partially dry or dry grassy areas; also in sparse, warm forests Open, lime-rich places

-

3

Additional Material A 1_3

Slugs

Dusky slug Black keel back slug

5 – 7 cm

10 – 20 cm (rarely up to 30 cm)

Grey field slug 3,5 – 5,5 cm

Great grey slug 10 – 15 cm (occasionally larger)

Lemon slug 3 – 5 cm

Darkfaced arion slug Red Slug

3 – 5 cm

12 – 15 cm (occasionally larger)

Marsh slug 1,5 – 2,5 cm

Portuguese slug 8 – 14 cm

Scale in 1:2 Huge animals are shown smaller shortest – longest observed animals

Snails – Additional Materal A 1_2

Additional Material A 1_3

Further information about the snails illustrated in Identification handout Slugs Species

L (c. in mm)

Identifying features

Black keel back slug Limax cinereoniger Great grey slug Limax maximus

100 - 200 (rarely - 300)

Grey-brown with spotted striped pattern to completely Structure-rich forests black; sole in 3 parts; sides of adult animals grey to black, light in the middle Light brown to grey with striking striped and spotted Varied biotopes, often near to pattern, sole plain and light coloured human settlement

Portuguese slug Arion lusitanicus Red slug Arion rufus Dusky slug Arion fuscus Grey field slug Deroceras reticulatum Lemon slug Malacolimax tenellus Dark-faced arion slug Arion distinctus Marsh slug Deroceras laeve

100 - 150 (occasionally larger) 80 - 140

Habitat

Way of living

RL BY -

Active at twilight and at night; in crevices in trees, under deadwood etc Active at twilight and at night; in crevices in trees, under deadwood or in old boards etc In contrast to the native red slug no summer dormancy – competitive advantage; eats the eggs of other snails In low-growing plants and 3 under deadwood

Colour of adult animals mid to dark brown, sometimes reddish, sole mostly dark grey. Young animals brownolive with striking brown patterning

Diverse cultural biotopes, increasingly crossing over to natural biotopes

Colour of adult animals varies: red, orange, brown, black; sole mostly light grey. Young animals mostly plain yellow, light orange, occasionally with pale bands Ochre-yellow to orange-brown, mostly with brown banding pattern

Diverse, mostly moderately damp biotopes (forests, hedges, fields) Needle and deciduous forests, On the ground, under deadalso hedges or bushes wood and climbing trees

35 - 55

Light cream-coloured to brownish, mostly with darker spotted patterning

Diverse cultural biotopes

In low-growing plants

-

30 - 50

Brownish to orange-yellow

Deciduous and needle forest

-

30 - 50

Dark grey to yellowish-grey with light yellow sole

Open areas among others

Feeds on fungi and others, algae and lichens In the leaf litter and on low-growing plants

15 - 25

Mid to dark brown, mostly with weak spotted pattern

Wet biotopes

Can spend long amounts of time in water

-

120 - 150 (occasionally larger) 50 - 70

Explanations: Endangered species: RL BY (= Red List Bavaria): 3 = endangered

Snails – Additional Materal A 1_3

-

-

Additional Material A 1_4

Water snails

Big-ear radix snail 1 – 2 cm

Common ramshorn snail 1 – 2 cm

Great ramshorn snail 2 – 3,5 cm

Lister‘s river snail 2,5 – 3,5 cm

Great pond snail

Common pond snail

Keeled ramshorn snail

1 – 2 cm

1 – 2 cm

1,5 – 3 cm

Stagnicola fuscus 6 – 12 mm

Faucet snail Lake limpet

Whirlpool ramshorn snail

Fountain bladder snail

6 – 10 mm

4 – 7 mm

5 – 7 mm

4 – 7 mm

White ramshorn snail 4 – 7 mm

River limpet

Moss bladder snail

3,5 – 6 mm

4 – 6 mm

Twisted ramshorn snail 3 – 6 mm

European stream valvata 3 – 4 mm

Small snails are shown bigger shortest – longest observed animals (size of the shell) Attention: For species with tower-shaped shells the height information can be found on the backsite of this sheet

Flat valve snail

Lesser pond snail

2 – 3,5 mm

2 – 4 mm

New Zealand mud snail 2 – 3 mm

Snails – Additional Materal A 1_4

Additional Material A 1_4

Further information about the snails illustrated in Identification handout Water snails Species Lister’s river snail Viviparus contectus Great ramshorn snail Planorbarius corneus Great pond snail Lymnaea stagnalis Big-ear radix snail Radix auricularia Common ramshorn snail Planorbis planorbis Common pond snail Radix balthica Keeled ramshorn snail Planorbis carinatus Stagnicola fuscus Whirlpool ramshorn snail Anisus vortex Faucet snail Bithynia tentaculata Fountain bladder snail Physa fontinalis Lake limpet Acroloxus lacustris White ramshorn snail Gyraulus albus Moss bladder snail Aplexa hypnorum River limpet Ancylus fluviatilis Twisted ramshorn snail Bathyomphalus contortus European stream valvata Valvata piscinalis Lesser pond snail Galba truncatula Flat valve snail Valvata cristata New Zealand mud snail Potamopyrgus antipodarum

Hxw Identifying features (c. in mm) 30 - 45 x 25 - 35 Greeny-brown to dark brown shell, mostly with 3 red-brown bands; shell pointed at the top (test this); corneous cover ~ 10 x 20 - 35

Disk-shaped, sold shell; brown, often with greenish or blackish coatings 30 - 60 x 15 - 30 Shell tapering to a point, with much wider last coil; young have a slim conical shape 15 - 25 x 10 - 20 Shell with small, pointed spiral and a much wider last coil 2 - 3 x 10 - 20

Spiral shell coils on one level; keel or edge on the outside, mostly towards the upper side, seldom in the middle 10 - 20 x 10 - 15 Shell with much larger last coil 1 - 3 x 10 - 15

Spiral shell coils on one level; sharp keel in the middle of the outside

10 - 25 x 6 - 12 Tall, conically shaped shell with fairly flat coils ~ 1 x 6 - 10

Tightly spiralled, thick disk-shaped shell

Habitat

Way of living

RL BY Still waters with many plants Feeds on green plants, also 3 in the Danube catchment area, filters particles from the Swabian-Bavarian hills, lakes water; ovoviviparus in the alpine foothills Still and slowly flowing Feeds on detritus waters Still and slowly flowing waters Grazes on aufwuchs (algae) and V with much plant material feeds on plant matter and detritus Still and slowly flowing waters Feeds on plant matter and detritus, grazes on aufwuchs (algae) Still and slowly flowing waters, Feeds on algae growth and V sometimes with muddy bottom, rotting plant matter smaller bodies of water Various still and slowly flowing Feeds on plant matter and smaller bodies of water, seldetritus, grazes on aufdom in larger flowing waters wuchs In the water plant belt of still Feeds on detritus V and slowly flowing, mostly larger waters Still waters with much plant Feeds on rotting plant V material material, grazes on the ground Still and slowly flowing waFeeds on algae growth and V ters with much plant material rotting plant material

8 - 11 x 5 - 7

Pointed oval shell with chalky cover

Running and still waters

Grazes and filters detritus. Very adaptable

-

7 - 12 x 4 - 7

Very thin-walled, very glossy, yellow-brown shell

Mostly feeds on detritus, also on algae

V

1-2x4-7

Bowl-shaped shell, the point is slightly bent towards the left back

Clear, still waters with much plant materials or slow flowing waters with much plant materials Still, rarely slow flowing waters

V

1-2x4-7

Spiral-shaped shell with a lattice structure

Still and slow flowing waters

Grazes for example on water plants, also roots or deadwood in the water Mostly feeds on detritus

Slim, reddish-brown shell shaped like a high tower; strongly glossy when fresh

Temporary and small bodies of water

10 - 15 x 4 - 6

2 - 3,5 x 3,5 - 6 Bowl- or cap-shaped shell with a point bent towards the right back

Flowing waters and the surf zone of lakes

V

Feeds on rotting plant 3 matter and grazes the bottom of the water Lives in hard substrate where it grazes on aufwuchs; rheophilic (prefers flowing water) Feeds on algae growth and V decomposing plant matter

1-2x3-6

Tightly would spiral-shaped, flat shell with a sharp keel on the outer side

Still and slow flowing waters with much plant material

3-5x3-4

Flat, conical shell with a round opening and cover

Feeds on detritus, needs oxygen

V

5-8x2-4

Slim, pointed conical shell with layered, offset coils

At the bottom of flowing waters and larger bodies of still water Temporary and small bodies of water, wet fields and marshes Sill and slow flowing waters, springs

Lives like an amphibian, likes to be out of the water

-

Feeds on detritus, needs oxygen

-

Freshwater (flowing and still waters) and stagnant water

Mostly feeds on detritus; give birth to live young

-

1 - 1,5 x 2 - 3,5 Flat, disk-shaped rolled up shell with a round opening and cover 4-6x2-3

Slim, pointy conical shell with cover

Explanations: ~ = approximately. Endangered species: RL BY (= Red List Bavaria): 3 = endangered; V = warning stage

Snails – Additional Materal A 1_4

Additional Material A 1_5

Molluscs

Zebra mussel 2,5 – 4 cm

Swan mussel bis ca. 20 cm

Asian clam 2 – 4 cm

Duck mussel 8 – 11 cm

European fingernail clam 10 – 12 mm

Greater European pea clam Painter‘s mussel

7 – 11 mm

8 – 11 cm

Lake fingernail clam 7 – 10 mm

Thick-shelled river mussel (strictly protected!) 5 – 7 cm

Scale in 1:2 Huge animals are shown smaller

Pea clam or Pea cockle 3,5 – 5 mm

shortest – longest observed animals

Snails – Additional Materal A 1_5

Additional Material A 1_5

Further information about the snails illustrated in Identification handout Molluscs Species Swan mussel Anodonta cygnea

Hxw Identifying features (c. in mm) 80 - 120 x - 200 Longish, egg-shaped, relatively thin shell; upper and lower edges parallel

Habitat

Way of living

Larger bodies of still water

Filterer, parasitic larvae (glochidia) cling to the fins of host fish

Still and slow flowing waters

Filterer, parasitic larvae (glochidia) cling to the fins of host fish

3

Elongated, tongue-shaped shell, when fresh greenishyellow patterning; upper and lower edges almost parallel. Whorl (part of the shell from the juvenile phase) has small, isolated chalky humps 30 - 40 x 50 - 70 Elongated elliptical to shorter egg-shaped solid shell with curved upper edge

In larger still and flowering waters

Filterer, parasitic larvae (glochidia) cling to the fins of host fish

2

Previously widespread in streams and rivers with clear, oxygen-rich water; today it is threatened with extinction

Filterer, parasitic larvae (glochidia) cling to the fins of host fish. Juvenile mussels at the bottom of the water sensitive to nitrate

1

15 - 20 x 25 - 40 Three-cornered, navicular shell with characteristic banding

Larger still and flowing waters Filterer, uses byssus threads to attach itself firmly to the substrate

-

Rivers and lakes

-

Duck mussel Anodonta anatina

50 - 70 x 80 - 110

Painter’s mussel Unio pictorum

30 - 40 x 70 - 100

Thick-shelled river mussel Unio crassus

Zebra mussel Dreissena polymorpha

Asian clam 20 - 35 x 20 - 40 Corbicula fluminea European 8 - 10 x 10 - 12 fingernail clam Sphaerium corneum Greater European 5 - 7 x 7 - 11 pea clam Pisidium amnicum Lake fingernail clam 7 - 8 x 7 - 10 Musculium lacustre Pea cockle 2,5 - 4 x 3,5 - 5 or Pea clam Pisidium casertanum

Rhombus-like, egg-shaped, relatively thick shell, with diverging upper and lower edges

Roundish, three-cornered, thick shell with bold ribs

Filterer. Spreads using free-swimming larvae Roundish-oval, bulbous shell Still and not too strongly Filterer. Mostly lives on the flowing waters bottom, but also on water plants Elongated oval-shaped, strong shell with superimposed Flowing waters and surf zones Filterer. ribs of lakes Prefers sandy ground Trapezoid-shaped roundish shell with crested, offset whorl Elongated egg-shaped or triangular shell

Smaller bodies of still water; also slowly flowing waters Still and flowing waters

Filterer

2 V

Filterer, euryoecious species (have a broad variety of living conditions)

Explanations: ~ = approximately. Endangered species: RL BY (= Red List Bavaria): 1 = threatened with extinction; 2 = critically endangered, 3 = endangered; V = warning stage

Snails – Additional Materal A 1_5

RL BY 3

Additional Material A 3_1

Outer features of a snails and slugs

Mantle

Head

Eye

Tentacle Foot

Respiratory Pore

Genital Pore

Mantle

Head

Eye

Tentacle Foot

Respiratory Pore

Snails – Additional Materal A 3_1