Land Snails of Cape Breton

BACKGROUNDThis key was produced from 1995 – present.It was written by Ryan Luedy and JeanMacMillan, two undergraduate biologystudents. All illustrations, unless otherwisenoted, were created by Basma Kavanagh.Financial support was provided by CapeBreton University and the Natural Sciencesand Engineering Research Council.

Cape Breton Island makes up roughly one-fourth of the Province of Nova Scotia. TheIsland is separated from the mainland by theStraight of Canso. Although a causeway hasbeen constructed across the straight in the1950’s, the two land masses have beenseparated from each other long enough toallow differences in fauna, including terrestrialmulluscs, to develop. Cape Breton containsspecies not found on the mainland and viceversa. There are a number of explanations forthis. One reason is that species radiating fromWestern Canada were halted by the straight.

Another reason is that extinctions may haveoccurred on Cape Breton Island but not onthe mainland or vice versa. As well, speciescould have been introduced to Cape BretonIsland via old settlements, like Louisburg, andnot introduced to the mainland. Again, theopposite may have happened, species mayhave been introduced to the mainland andnot Cape Breton.

Although the number of mollusc speciesfound on Cape Breton Island and in the restof Nova Scotia is small when compared toother places in the world, there are significantnumbers of species present to warrant studyof them. That is why this key to the LandSnails and Slugs of Cape Breton has beenconstructed, to encourage people to studythese unique creatures and become aware oftheir presence.

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Land Snails of Cape Breton

INTRODUCTIONLand snails are soft unsegmented animalsthat belong to the phylum Mollusca. Asindicated in figure 1, land snails have aventral foot, four tentacles: an upper pairthat have eyes and a lower pair that lackeyes, and a mantle that contains theanimal’s internal organs, and is usuallyenclosed in a calcareous shell.

These animals are hermaphroditic,meaning there are no males or females;every individual has both male and femalereproductive organs. However, two snailsor two slugs of the same species mustmeet in order to lay eggs, they cannotself-fertilize. For these animals, thisinsures that when two animals meet, theycan reproduce; they do not have to lookfor a mate of the proper sex.

Land snails and slugs can be foundalmost anywhere, but especially in thoseareas that offer shelter, moisture, food,

and for snails a source of calcium, usually in the form of limestone. Land snails can be found most easilyon foggy / rainy days in the spring andsummer. They tend to be on low green plants,tree trunk bottoms,and in the first fewcentimeters of soil. Therefore, snails can becollected in a couple of ways.

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Land Snails of Cape Breton

INTRODUCTIONOne way is to pick them up as you closelyexamine the ground vegetation on adamp/rainy day. Another way is to shakesoil/leaf litter samples on a mesh screen(about .5 cm holes), collect the materialthat passes through, and then look throughit under a microscope. This techniqueworks very well for small species. Somesnail shells can be smaller than 1mm, andnearly impossible to collect any other way.

After snails have been collected, they canbe kept live or can be preserved. To keepthem alive, place them in a cool, moistplace with some food. Be sure to containthem in a sealed container that allows airto enter. Fresh lettuce and carrot slicesseem to keep them happy. Some wetwoodchips, sand, or soil should be placedin the bottom of their home, to keep themmoist.

To preserve snails, one of two things canbe done. They can be left to dry out. Smallones can be dried as is. After a period of

time, the dried body can be removed from theshell or it can be left alone. For larger species, itis best to remove as much of the body aspossible with forceps or a bent pin before drying.The second way to preserve snails, and the onlyway to preserve slugs, is to store them in vials ofpreservative.

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Land Snails of Cape Breton

IDENTIFICATIONIn order to identify snails and slugs you must first become familiar withsome important features of the animals. The following figures will illustratethe important features used in identification of land snails and slugs.

General external features of typical snail Method of counting whorls when snailis viewed from above

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Land Snails of Cape Breton

IDENTIFICATIONIn order to identify snails and slugs you must first become familiar withsome important features of the animals. The following figures will illustratethe important features used in identification of land snails and slugs.

Shell TerminologyMethod of measuring shell

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Land Snails of Cape Breton

IDENTIFICATIONOn order to identify snails and slugs you must first become familiar withsome important features of the animals. The following figures will illustratethe important features used in identification of land snails and slugs.

Types of Shells (viewed from below)

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Land Snails of Cape Breton

IDENTIFICATIONOn order to identify snails and slugs you must first become familiar withsome important features of the animals. The following figures will illustratethe important features used in identification of land snails and slugs.

Shell Periphery Types Shell Shapes

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Land Snails of Cape Breton

GLOSSARYAngular Periphery: See periphery types.

Apex: The top or first whorl on the shell thatis farthest away from the aperture.

Body Whorl: the last outermost whorl of asnail shell.

Breathing pore: An opening in the mantleedge that serves for air passage into the lungcavity.

Columella: the edge on the inner side ofthe aperture.

Foot: Located towards the back of the snailon the ventral surface. The foot is usedmostly for locomotion as well as digging andgrasping food.

Growth Lines: A thin line on the surface ofthe shell indicating a period of rest in thegrowth cycle.

Hirsute: covered with small hairlikeprojections.

Imperforate: Lacking an umbilicus on theunderside of shell.

Keel: A sharp ridge down the dorsal surface ofa slug, usually restricted to the posterior end.

Lamella: A fold or raised tooth inside theaperture.

Lip: the edge of the shell on the outside of theaperture.

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Land Snails of Cape Breton

GLOSSARYMantle: a soft outer covering of the visceral massof the mollusc; in snails it is under the shell.

Moderately Unbilicate: see umbilicus

Narrowly Umbilicate: see umbilicus

Nuclear Whorl: The first two whorls of the snailshell.

Ovate: Oval shaped.

Pedal Groove: a longitudinal groove in the sideof the foot of a snail or slug that marks theboundary of foot sole and side.

Periphery: the outer edge of the body whorl.

Pigment Band: a longitudinal band or strip ofcolour found on the sides or dorsal surface ofslugs.

Radiating Indented Lines: Evenlyspaced, impressed lines of the shell of a snailthat are perpendicular to the whorls.

Reproductive Pore: in snails thereproductive pore is located in the headregion. In slugs the reproductive pore islocated beside or below the breathing pore.

Reflected Lip: The shell is turned awayfrom the snail at its end, the lip.

Ribs: Transverse projections on the outsideof the snail shell, evenly spaced, andprovided the shell is larger than a fewmillemetres, can be seen with the naked eye.

Round Periphery: See periphery types.

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Land Snails of Cape Breton

GLOSSARYSpiral Lirae: raised lines or ridges on thesurface of the shell that run in the samedirection as the whorls (spirally).

Striae: faint lines within the structure on asnail’s shell.

Subangular Periphery: See peripherytypes.

Suture: the junction between twosuccessive whorls.

Umbilicus: a hole or opening in the centerof the underside of the shell. The terms widelyumbilicate, narrowly umbilicate and moderatelyumbilicate refer to the relative width of theumbilicus compared to the diameter of theshell. Those that are widely umbilicate haveand umbilicus that is greater than 1/2 shelldiameter. Narrowly umbilicate shells have anumbilicus that is less then 1/3 and moderatelyumbilicate shells fall in between.

Widely Umbilicate: See umbilicus

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Land Snails of Cape Breton

KEY

1A • External Shell Present 1B • External Shell Absent

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KEY

2A • Shell distinctly wider thanhigh

2B • Shell higher than wide, or aswide as it is high

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Land Snails of Cape Breton

KEY

3A • Shell as high as wide 3B • Shell distinctly higher thanwide

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KEY

4A • Aperature length morethan half the shell length

4B • Aperature length less thanone half the shell length

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Land Snails of Cape Breton

KEY

5A • Aperature withoutlamellae

5B • Aperature with lamellae

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KEY

6A • Shell is spindle shaped,very glossy, tan and 5–7.5 mmin height

6B • Shell cylindrical shaped, tanwith white streaks, and is 5–7.5 mmin height

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Land Snails of Cape Breton

KEY

7A • Mantle covers nearly entireanimal

7B • Mantle covers only an anteriorportion of the animal

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Land Snails of Cape Breton

KEY

8A • Slug is small, 15mm or less 8B • Slug is large, 50mm or greater

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Land Snails of Cape Breton

KEY

9A • Breathing pore located inanterior portion of mantle, backnot keeled and posterior end ofbody rounded when viewed fromabove

9B • Breathing pore located inposterior portion of mantle, backkeeled at posterior end of bodywhen is pointed when viewed fromabove

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KEY

10A • Slug 70mm or greater in lengthwhen extended

10B • Slug 50 mm or less in length whenextended

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KEY

11A • Slug 35-50mm in length, mantlesituated near head, animal exudesmilky slime when irritated

11B • Slug 15-30mm in length, mantlesituated slightly back from head, animalexudes watery slime when irritated

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Land Snails of Cape Breton

KEY

12A • Shell is 15mm or greater inwidth

12B • Shell is less than 15mm inwidth

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KEY

13A • Shell with raised spiral lirae 13B • Shell without raised spirallirae

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KEY

14A • Shell with ribs and withouta reflected lip

14B • Shell without ribs

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Land Snails of Cape Breton

KEY

15A • Shell without a reflected lip 15B • Shell with a reflected lip

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KEY

16A • Shell white in colour 16B • Shell not white in colour

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KEY

17A • Snail without pedal groovesand 7–9mm in width

17B • Snail with pedal groove andless than 6mm in width

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Land Snails of Cape Breton

KEY

18A • Snail with radiating indentedlines

18B • Snail without radiatingindented lines

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KEY

19A • Shell from 4.5–5.6mm indiamter, faint yellow or brownish

19B • Shell 2.2mm in diameter, nearlycolourless

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KEY

20A • Shell with whorls slowlyincreasing in width, aperaturesmall

20B • Shell with whorls rapidlyincreasing in width, aperaturerelatively large

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KEY

21A • Shell with ribs 21B • Shell without ribs

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KEY

22A • Shell with reflected lipand lamellae in aperature

22B • Shell without reflected lipand without lamellae in aperature

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Land Snails of Cape Breton

KEY

23A • Breathing pore locatedbelow right mantle pigment band

23B • Breathing pore located inright mantle pigment band

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KEY

24A • Slug 20-40mm in length,sole of foot yellow and animalalmost black in colour

24B • Slug 60-80mm in length, soleof foot pale yellow and animalyellowish brown

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Land Snails of Cape Breton

KEY16 • Succinea spp.

Length: 7.2mm; (N=4) (x=6.4mm)

Shell with 2.5 whorls, very thin, pale yellow,aperture ovate, lip sharp. Note: speciesidentification is not well known and therefore onlygenus is given.

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Land Snails of Cape Breton

KEY17 • Vertigo pygmaea (Draparaund)

Length: 2.0mm; (N=2) (x=2.0mm)

Shell with 5 whorls, chestnut-brown, lip reflected,containing lamellae.

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KEY18 • Cochlicopa lubrica (Müller)

Length: 5.0-5.6mm; (N=6) (x=5.1mm)

Shell with about 5–5.5 whorls, light tan, very glossy, lipnot reflected by thickened within, columell slightly sinuate.

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Land Snails of Cape Breton

KEY19 • Columella edentula (Draparnaud)

Length: 1.75–2.5mm; (N=4) (x=1.8mm)

Shell with about 5.5–6.5 whorls, cylindrical, perforate, cinnamon,thin, smooth but with irregular growth lines. Shell length given isfor adults, but smaller juveniles are more commonly found.

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Land Snails of Cape Breton

KEY20 • Philomycus fluxuolaris (Rafinesque)

Length: 50mm; (N=4) (x=45mm)

Slug is dark brown with lighter flecks, faint darkerbands down sides, foot fringe has reddish tinge,mantle covers nearly entire body.

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Land Snails of Cape Breton

KEY21• Pallifera dorsalis (Binney)

Length: 6.5-15mm; (N=2) (x=unknown)

Slug is usually gray or bluish-gray with darkercoloured sections, foot sole white, may have a darkline along dorsal surface of mantle.

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Land Snails of Cape Breton

KEY22• Limax maximus (Linné)

Length: 82-120mm; (N=7) (x=118mm)

Slug is light to dark brown, black spots on bothmantle and body, body not banded, mucuscolourless.

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KEY23• Deroceras reticulatum (Müller)

Length: 16-28mm; (N=14) (x=24.3)

Slug is light coloured, darker inconspicuousmarkings on entire body, commonly called the Grey Garden Slug.

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Land Snails of Cape Breton

KEY24• Deroceras laeve (Müller)

Length extended: 9-24mm; (N=4) (x=15.2)

Slug usually solid coloured, dark brown to black,similar to Deroceras reticulatum but smaller andmore uniform in colour.

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KEY25 • Cepaea hortensis (Müller)

Diameter: 13.7–19.5mm; (N=25) (x=16.9mm)

Shell with 4–4.5 whorls, banana yellow, may have 1–5 brown bands oneach whorl, may be translucent or opaque, aperture lip reflected and whitewhen viewed from inside, commonly called the white-lipped garden snail.

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KEY26 • Helicodiscus parallelus (Say)

Diameter: 3.2–3.5mm; (N=1) (x=3.2mm)

Shell with 4–4.5 whorls, pale green, spiral lirae poorly developed onfirst one or two whorls.

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KEY27 • Discus catskillensis (Pilsbry)

Diameter: 3.7–4.2mm; (N=16) (x=4.1mm)

Shell with 4 whorls, pale brown, angular periphery, wide umbilicus.

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KEY28 • Vallonia pulchella (Müller)

Length: 2.2mm; (N=4) (x=2.1mm)

Shell with about 3 whorls, whitish, faint growthlines, moderately umbilicate.

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KEY29 • Hawaiia minuscula (A. Binney)

Length: 2–2.8mm; (N=1) (x=2.1mm)

Shell with about 3.5–4.5 whorls, pale whitish, distinctgrowth wrinckles, umbilicus about 1/3 shell diameter.

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KEY30 • Trichia (Trichia) hispida (Linne)

Length: 6.1–8.5mm; (N=21) (x=7.3mm)

Shell with 5–6 whorls, pale cinnamon-brown, roundedwhorls, hirsute shell condition remaining in adults.

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KEY31 • Glyphyalinia indentata (Say)

Diameter: 4.7–7.1mm; (N=7) (x=3.9mm)

Shell with 4.5–5 whorls, tan, translucent, radiating indentedlines evenly spaced, faint growth lines and stiae also visible.

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KEY32 • Nesovitrea binneyana (Say)

Length: 3.5-5.3mm; (N=3) (x=3.1mm)

Shell with 3.5–4 whorls, almost colourless, faint green, verysimilar to Nesovitrea electina.

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KEY33 • Zonitoides arboreus (Say)

Diameter: 5-6mm; (N=34) (x=3.8mm)

Shell with 4.5-5 whorls, brownish in colour, faint spiralstriae.

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KEY34 • Nesovitrea electina (Gould)

Diameter: 4.6-5.2mm; (N=4) (x=4.8mm)

Shell with 3.5 whorls, pale green to brown,moderately umbilicate.

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KEY35 • Euconulus fulvus (Müller)

Diameter: 2.6mm; (N=1) (x=2.6mm)

Shell with 4.5–6 whorls, tan, conical spire, lip thin,periphery rounded or sub angular.

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KEY36 • Strobilops labryinthica (Say)

Diameter: 2.3-2.5mm; (N=4) (x=2.2mm)

Shell with 5.5 whorls, light brown, ribs absent on theinderside of shell, spire conically shaped, narrowly perforate.

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KEY37 • Zoögenetes harpa (Say)

Diameter: 1.5-2.5mm; (N=9) (x=2.1mm)

Shell with 4 whorls, olive-brown, last two whorls sculpturedwith ribs, first few smooth, lip thin, not reflected.

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KEY38• Arion fasciatus (Nilsson)

Length extended: 20-46mm; (N=16) (x=34.3)

Slug pale gray to black with a porcelain white foot, muscus clear.Reproductive pore located in front of breathing pore, breathing porebelow right pigment band. Sides of body have dark longitudinalbands.

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KEY39• Arion hortensis (Ferussac)

Length extended: 20-40mm; (N=3) (x=30)

Slug dark gray to black, posterior end rounded when viewedfrom above, right mantle pigment band thick, dark andcovering breathing pore.

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KEY40• Arion subfuscus (Draparnaud)

Length: 60-80mm; (N=11) (x=64)

Slug yellowish, mantle pigment band faint, foot pale yellow, breathing porewithin pigment band. When killed in salt water or deoxygenated water, itballoons out a reproductive pore, located just below the breathing pore on theright side.

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