Study The Slug

The spotted leopard slug.

       The  air-breathing  molluscs  (Pulvionates)  in  which  the  shell  is  internal  or entirely  absent  are  popularly  called  slugs  ( Limacidce ).  On  the  front  part  of the  back,  near  the  head,  these  animals  have  a  fleshy  plate,  the  mantle,  near the  right  edge  of  which  is  the  opening  or  pore  by  which  they  breathe.  Slugs closely  resemble  snails  in  structure ;  indeed,  all  the  six  families  into  which slugs  may  be  divided,  seem  to  have  been  derived  separately  from  shell-bearing ancestors.  They  love  dark  and  damp  places,  and  crowd  together  in  cellars and  outhouses  and  under  planks  and  stones.  As  they  hide  themselves  during  the  day  and  only  issue  forth  at  night  the  damage  done  by  them  is  often attributed  to  other  creatures,  though  the  presence  of  slugs  may  be  recognized by  streaks  of  slime  in  the  neighborhood.  All  the  air-breathing  molluscs  can secrete  mucus  from  their  body,  and  in  slugs  this  power  is  highly  developed. When  the  animal  is  irritated  the  secretion  of  mucus  is  greatly  increased,  the secretion  being  partly  defensive.  They  use  the  secretion  in  another  way,  for these  animals  will  lower  themselves  from  a  tree  or  shrub  by  means  of  threads of  mucus.  Like  snails,  slugs  often  lift  their  heads  and  move  their  tentacles in  search  of  objects  around  them.  When  they  are  frightened  they  draw their  heads  under  their  mantles  and  contract  their  foot.  They  lay  their  eggs, which  look  like  small  oval  bags  of  jelly,  in  moist  places.  The  eggs  are  from twenty  to  forty  days  in  hatching,  and  the  young  slug  attains  its  full  size  in  a year. 

Required for Observation: A  live  slug;  a  cabbage  leaf;  and  a  live snail.  A  picture  of  the  slug,  and  a  sketch  of  its  teeth. a rasp

Method of Student Observation:

• Compare  the  body  of  the  slug with  that  of  the  garden  snail.
• Show  the  sticky  nature  of  the slime,  and  point  out  that  the  slug will  sometimes  let  itself  down  from  a tree  by  a  thread  formed  of  its  slime.
• Compare  with  the  head  of  a snail.  Explain  that  the  horns  are pulled  inside  out  as  they  are  retracted  ;  and  imitate  the  movement by  pulling  the  finger  of  a  glove  inside out  by  means  of  a  string  attached  to the  tip.
• Exhibit  a  diagram  of  the  teeth.
• The  children  should  watch  the slug  as  it  crawls,  and  observe  the slimy  track  made  by  it.  They  should also  be  allowed  to  see  the  wave-like contraction  of  the  under  surface  as the  slug  crawls  on  a  piece  of  window-glass. 
• Note  that  the  slug  is  an  air-breathing  animal,  and  that  it  cannot live  in  water.  Point  out  the  pulmonary  aperture  on  the  right  side.
  
• Show  a  rasp,  and  compare  the action  of  the  slug's  teeth  with  that of  the  rasp.
• The  children  should  be  encouraged  to  seek  the  slug  in  its  haunts, and  observe  its  habits  in  the  garden or  during  their  rambles.
• Slugs'  eggs  should  be  procured  if possible.  They  may  be  found  under stones  and  other  objects.
  

How To Grade Study Notes For Student Journals: Every student will need a journal to write in weekly for this online nature study series. Teacher will assign the weekly content in advance.

• Make sure the facts are: written in complete sentences, the first word of each sentence capitalized, and a period should be included at the end of each sentence.
• Spell check your vocabulary and write the words correctly.
• Dress up your journal entries with student clip art, drawings of your own in color or in black and white.
• Student may also include photographs of their own taking for extra credit.

Look for the following facts about slugs inside of student journals. Assign a point value to the quality of the content.

• General  form - Body  elongated and  tapering  before  and  behind. Convex  above  and  flat  beneath.
• Skin  -  Soft  and  slimy.  In some  species  much  wrinkled.  Color whitish,  yellowish,  brown,  or  black, according  to  the  species.
• Head - Provided  with  four  retractile  horns - -two  longer  and  two shorter.  Horns  used  as  feelers,  and the  eyes  are  situated  at  the  tip  of the  longer  pair.
• Mouth  on  the  under  side  of  the head,  and  provided  with  numerous small  teeth  in  parallel  rows.
• Crawling -  The  slug  crawls  on its  belly,  moving  itself  along  by  a wave-like  contraction  of  the  muscles of  its  under  surface.  As  it  crawls it  leaves  behind  it  a  streak  of  slime, which  soon  hardens  on  exposure  to air.
• Breathing - The  slug  breathes by  means  of  a  lung,  the  air  passing through  an  opening  on  the  right  side of  the  body.
• Feeding -  It  feeds  on  various vegetable  substances,  biting  off  small pieces  with  its  teeth.
• The  Slug  at  rest. The  slug  does not  like  the  light  and  heat  of  the sun.  It  hides under  cover  during the  day,  and  crawls  about  and  feeds at  night.  It  goes  to sleep  all  winter, taking  no  food.
• Young - The  young  of  the  slug are  produced  from  eggs.  They  do not  undergo changes,  like  insects, but  are,  from  the  first,  of  the  same form  as  their  parents.

The finished slug craft
photographed outdoors

Video at Youtube for Students to Watch:

1. Solar-powered slugs by SciShow Kids
2. Banana Slugs: secret of the slime by Deep Look
3. Common Leopard Slugs Are Cool! by Discover Downeast

The Life Cycle of The Slug: Students will need writing and drawing tools, two white paper plates, scissors, white school glue and one brass-plated fastener. The teacher should supply the two paper plates and fastener per student. Draw the different stages of a slugs' life on the first paper plate dividing these into separate pie shaped grid. Color the second paper plate with leaves and twigs; the kinds of natural stuff found on a forest floor. Cut away one small pie shaped window so that the life stages may be viewed through the top paper plate after it has been joined to the first using a fastener at the center of both.  

• Watch a life-cycle film of slugs from BBC Earth.

Craft a Slug From An Egg Carton: You will need the following supplies: masking tape, a 2 chenille stems. recycled cardboard egg carton, white school glue, tissue paper, acrylic paints, and Mod Podge

Step-by-Step Instructions:

Left, the cardboard egg carton cut apart and chenille stem threaded through units.

 

        With scissors cut the cardboard egg carton apart into multiple units. Clean up the edges to make these units neater and relatively of the same size and proportion. Poke a whole in each unit at it's center using the sharp end of your scissors. 

       Wrap the tip end of a chenille stem just outside the snail's end unit to hold the wire in place while the units are threaded onto it. You will be threading these while wadding three inch long pieces of masking tape and tucking it between the units. 

       Position the units in a curved shape as you go. Use more masking tape to adjust the shape of the slug and reinforce it as you proceed.

       Bend the chenille wire to hold the units in place and shape the four horns at the end of the slugs' head.

See the paper mache slug prior to painting after it has been covered with a layer of glue and tissue.

 

       Cover the egg carton units with a few layers of tissue paper and white school glue. Let this pretend slug dry over night before painting it.

The slug as seen from the top, side and bottom after painting it.

       I painted my version of a slug using multiple tan and brown colors because it is to represent a spotted leopard slug. However, students may choose to paint a banana slug yellow or some other kind of slug in it's own color variations. Once the painted surfaces are dry, cover the entire slug in stages with Mod Podge to seal it properly.

Free Student Clip Art: Clip art may be printed from a home computer, a classroom computer or from a computer at a library and/or a local printing service provider. This may be done from multiple locations as needed because our education blog is online and available to the general public.

Illustrated in the clip art above are the anatomical features of all slugs.