Introductory Level

Observing earthworm locomotion

Introduction

Introducing students to activities that involve close study of animal behaviours is worthwhile in itself. Ensuring that students handle the animals appropriately, make good observations and record those observations clearly takes time and effort. If you are collecting worms as part of the OPAL survey you could use this as an extension activity for some students. (see link below: Data collection runs until 2012 and the first earthworm survey data will be collated at the end of May 2009.) If you’ve never heard the noise a worm makes when it moves on a piece of paper, a surprising new experience awaits you!

Lesson Organisation

This will depend on whether you choose to collect some worms in advance, or include worm collection as part of the lesson. If you have the support of an assistant, perhaps a small group could go to collect worms while the rest prepare to observe them. If you have enough worms for students to work in pairs, it is worth spending 15 minutes observing the worms’ movement (and listening to the sound of worm bristles on paper) and a further 15 minutes drawing diagrams to show how the worm moves. Use the sequence of still images provided to direct students who are finding it difficult to focus on the stages of locomotion.

Apparatus And Chemicals

For the class – set up by technician/ teacher:
To collect the worms:
Spade (note 1)
Mustard powder (optional – see Preparation)
Plastic tub (1 litre plus) plastic tub with small air holes in lid and sides containing potting compost

For each group of students:
Glass sheet (note 2)
Earthworms

Health & Safety

Read our health and safety guidelines

Take care with glass sheets
Take hygiene precautions after digging up soil – wash hands thoroughly with soap and hot water.

Technical Notes

1 In choosing a site to dig, be aware of the risk of picking up infections from animal faeces, and the risks from sharp buried objects. If you expose broken glass or metal objects, choose another site immediately. Ensure everyone who has handled the soil washes their hands with soap and hot water on return to the laboratory and before leaving the lesson.

2 If you use a sheet of glass it should have milled or taped edges. Students should handle it with care and be aware of your laboratory procedures for dealing safely with broken glass in case of accident.

3 Handling worms safely (from the worms’ perspective): Keep the worms in a humid, dark container, with some sphagnum moss (not sphagnum moss peat).

Ethical issues

Teachers should be careful to introduce these animals in a way that promotes a good ethical attitude towards them and not a simply instrumental one. Although they are simple organisms that may not 'suffer' in the same way as higher animals, they still deserve respect. Animals should be returned promptly to their original environment after the investigation. This supports ethical approaches that are appropriate to field work where collected animals are returned to their habitat after observations have been made.

Procedure

SAFETY:
Handle sheets of glass with care and clear up any breakages safely.
After handling soil, wash hands with soap and hot water.

Preparation

a Collect worms by digging in the soil in some part of your school grounds or a domestic garden. If you find only a few worms, these two methods might encourage more to surface.

Method 1: Rhythmic rocking
Gather a group of 8-20 students in a circle in the area where you want to collect worms. Ask them to rock gently back and forth on the soles of their shoes, from heel to toe and back again. There is no need to stamp or make vigorous movements, just rock steadily for a couple of minutes. Worms will surface.

Method 2: The OPAL website worm survey suggests the following technique to collect worms. Dig a pit 10 cm deep and 20 cm x 20 cm and collecting the worms from the soil you extract. Then it suggests adding the contents of a sachet of mustard (as supplied in restaurants) to 750 cm³ of water and pouring that into the pit to encourage deep-dwelling worms to surface. This is not toxic and does not destroy grass or other plants. The mustard is a slight irritant to the worms, but preferred to other chemicals (including washing up liquid) which are more harmful.

Investigation

b Put a worm in the middle of a large sheet of paper. Observe its movements and try to describe them. Listen carefully for the sounds the worm makes on paper.

c Transfer the worm to a sheet of glass. Observe how it moves now. Try to describe any differences.

Teaching Notes

There are clear diagrams of the stages of worm locomotion in most traditional biology texts.

Below are some photographs, and included in this simple
Powerpoint presentation (194 KB).

If there is no background noise, you can hear worms moving on paper – a faint scratching sound as their bristles (called chaetae, chetae or setae!) engage with the paper. Worms cannot get a grip on glass and so cannot move over it.

The sequence of movement – engaging the chetae in one segment followed by muscular contraction to pull the rest of the body to that point – is fascinating to observe. Below is a short video.

The materials on the OPAL website allow you to take this further and carry out an extensive investigation of earthworms (identifying different species) and their environment (identifying soil types and key features of soil.

Health & Safety checked, May 2009

Web Links

www.opalexplorenature.org
OPAL is a Big Lottery Funded project that aims to create and inspire a new generation of nature-lovers by getting people to explore, study, enjoy and protect their local environment. Over the next few years they will be running five surveys across England to learn more about our environment, and they would like everyone to get involved. The soil and earthworm survey is the first and you can join in from March 2009 until 2012, with the first collated results available from May 2009.

The survey pack includes record sheets and details of how to dig for worms. It also includes a detailed key to identify about 13 common species of worm. This raises children’s awareness of biodiversity and encourages them to look more closely at worms.
An air survey to improve our knowledge of air pollution by recording lichens, an important indicator species starts in September 2009. A water survey starts in May 2010, using animals in the water to find out about the health of our lakes and ponds. A biodiversity survey starts September 2010 followed by a climate survey from March 2011.

CLEAPSS materials: CLEAPSS Guide L275: Science with minibeasts: Earthworms
This is a comprehensive guide with details of how to collect and keep worms safely (from your point of view as well as the worms’) and suggestions for a variety of observations and investigations of worm activity.

Email this page