Snail Anatomy + Snails & Slugs Science Homeschool Unit Study

Today's lesson plan {Snail Anatomy} is a sneak preview of my Snails & Slugs Science Unit Study! It's one of my fun homeschool unit studies--scroll to the very end to learn more about this unit!

This snail anatomy lesson (and the whole snail unit) is perfect for elementary aged kiddos who would rather play with snails and check out their shells than simply read about food webs! You can learn A TON by doing your own investigating! is...

Lesson 1: Snail Anatomy & Observations

Science Topics: Scientific Method (observation, predictions, analysis, critical thinking), sorting, senses & sensory organs, comparing & contrasting, characteristics of objects and organisms, physical characteristics


  • Paper plates, boxes, or something else to hold the snails you find
  • A place to find snails or slugs
  • Snail Anatomy picture & description (below in lesson)
  • Optional: ruler, small scale (digital or balance), clear glass plate or pan, Snail Observation Lab

Part 1: Collection.  Go outside and collect 10-20 (or as many as you can) snails and slugs. Under wood or rocks is a great place to look! Place the snails and slugs on a paper plate or in a cardboard box where you can observe them. Optional: If you set the snails on a clear glass plate or pan you can see through the glass and look at the foot as they crawl!

Part 2: Observation. Discuss the parts of the snail you can see. What do the shells look like? What are the snails doing? How are they similar or different to each other and to people? What do you notice about them moving?

Hint: If they aren’t moving, set them down in a warm, sunny spot. Snails “hide” inside their shell when they are concerned about predators or if the temperature is too cold. They “seal” themselves in with an “operculum,” but can easily come back out when they feel warm and safe.

How big are they? Physical characteristics or physical properties are things you can observe, like size, color, or weight. What do you think the different parts of the snails do? How can you sort them? (by physical properties like color, size, weight, etc)

Optionally, measure them with a ruler and/or a scale.

Part 3: Anatomy. Use the image and information below to identify the eyes, nose (if present), mouth, shell, and foot. If you have slugs, find the pneumostome. What do each of these parts do? Which are unique to snails and slugs?

Optionally, fill out the Snail Observation Lab.

1- Eyes - at the tips of the long tentacles.

2- “Nose” - at the end of the short tentacles. The tips of the second (smaller) pair of tentacles have olfactory glands on them and work like a nose.  Not all snails have them.

3- Mouth - near “bottom” of head. Even though it's in a spot you'd expect to find it, the mouth can be tricky to find on very small snails.  Look closely under both tentacles!  The mouth is just for eating, not breathing!

4- Foot - the soft “body” of the snail. The foot is the big muscle that crawls along the ground (or wall or plant...).  It moves by contracting and expanding.  It also has a gland to make mucus.  Mucus smooths the path for the snail and makes it easier for the snail to move.

5- Pneumostome - under the shell, easier to see in slugs. The pneumostome is a small pore (or opening) for breathing.  The pneumostome connects to the snail's one lung and lets the snail breathe.  It is on the snail's right side, but it is difficult to see the pneumostome because the shell often covers it.  Slugs also have a pneumostome in a much easier-to-see spot.  The pneumostome can be opened and closed.

6- Shell - hard protective covering. The shell is the most stunning feature on a snail!  Some can grow quite big, some have gorgeous stripes, and some are very plain.  The shell grows with the snail.  New layers of shell are added on at the top of the opening where the snail comes out of the shell, creating a spiral pattern as time goes by. In order to make the shell, the snail must eat calcium.  It usually gets calcium by eating dirt.

 One more thought on anatomy:
Most kids want to know if their snails are boys or girls.  The truth is, most snails are hermaphrodites (they have both male and female parts).  Apple snails (also called Mystery Snails) are a notable exception--they can change genders!  Here is a good explanation on how to identify apple snail gender.

Land Snail Internal Anatomy, for Older or Advanced Kids:

Image Copyright Information: By Original by Al2, English captions and other edits by Jeff Dahl [GFDL ( or CC BY-SA 4.0 (], from Wikimedia Commons:

Internal Anatomy Fun Facts:

Heart: Snail hearts have two chambers: a ventricle and an atrium. There is usually a blood vessel that connects the heart to the lung, but then the blood circulates throughout the body, washing over the different organs without going through blood vessels.

Lung: Land snails usually have one lung. Sea snails use gills to breathe!

Cerebral Ganglia: This group of nerves is like a simple brain. Some snail species’ brains are more complex than others, and some snails have even been trained! Scientists are even studying snails memories to learn more about human brains (read about one study here)!

Mouth: Snail “teeth” are actually a special organ called the radula. It is like sandpaper stretched inside the mouth. The radula is covered with very tiny teeth that scrape food into the mouth while the jaw can break off chunks or small bites.

Waste: Land snails reabsorb most moisture in their bodies, so they do not urinate separately from solid waste. “Poop” comes out the anus on the side of the shell and falls to the ground.

I hope you had a great time investigating snail anatomy!! This is the first lesson in the Snails & Slugs Science Unit Study. The unit includes 4 hands-on lessons and a set of printable bonus activities!  It's perfect for homeschool families and co-ops.  Click here to learn more!

Are you looking for more homeschool unit studies or themed units for elementary and middle school kids? Be sure to click here and check out our growing collection!

Happy Educating!
Carla & the kids who don't sit still