Webs of life

The plants and animals of a pond are all connected in a complex food web. This means that they all depend on each other - if any species is added, removed or affected in any way there will be an effect on all others.

Simplified pond food webs give some idea of these relationships. Food chains are further explored in the "What eats what?" activity sheet later in the pack.

Most published pond food webs include fish, which is a bit misleading as most ponds don't contain fish. The average pond - shallow, isolated from running water and subject to regular drops in water and oxygen - does not naturally support a population of fish. Artificially introducing fish to a pond has disastrous consequences for the natural community of a pond, as consideration of its food web will show. In your own food web work you should make this point and replace fish with other carnivores such as amphibians.

It is important to note that the pond food web connects with food webs on land (through creatures which move between land and water) and ultimately with humans.

Aims: To help children understand the interdependence of all life through feeding relationships.

What's in a word?

Fashions change with respect to the preferred names for each level of the food hierarchy. The terms used in the National Curriculum (as at January 1999) are underlined in the following account.

Plants are able to make basic foodstuffs from water and carbon dioxide, using energy from the sun, in the process called PHOTOSYNTHESIS.

The plants provide food for plant-eating animals and are referred to as PRODUCERS.

Plant-eating animals are known as PRIMARY CONSUMERS or HERBIVORES.

These are in turn consumed by meat-eating animals, termed as SECONDARY CONSUMERS or CARNIVORES.

Completing the FOOD CYCLE are SCAVENGERS and DETRITIVORES which feed on waste and dead material (DETRITUS, DEBRIS), returning it to other FOOD CHAINS.

Some animals eat a bit of everything (plant, animal and sometimes dead material) - we call them OMNIVORES or just CONSUMERS.

Activities

1. Making food chains and webs

See the ART, DESIGN, TECHNOLOGY AND PONDS section.

2. Webbing game

Stand pupils in a circle with the teacher at the centre. The teacher asks one pupil to name a species found in the habitat under study. That pupil holds onto the end of a ball of string or wool, which is then passed backward and forward between pupils as each volunteers to represent a species which eats, or is eaten by, the last named. In this way every pupil becomes connected with the string. Some species may be mentioned more than once, in which case the web becomes more complex. One species in the web should then be represented as being in decline by asking the appropriate pupil to sit down. Each pupil who feels a tug on the string as a result should also sit down, and so on; every pupil should end up sitting, as they are all connected. Making sure that one of the species in the web is a human will help demonstrate that our impact on other species affects ourselves as well.

Pond Pack Introduction Why study ponds? Pond-dipping Safety for teachers Safety for kids Animal variety Moving and breathing Cycles of life Webs of life Plant life Maths English Geography History Art and design Make a pond Plant identification Animal identification Activity sheets Bug dial Where to go Acknowledgements EDUCATION NATURE SEARCH . . . . . . . . .