Abstract

Objective

In this project, you will make a Berlese funnel to investigate micro-invertebrates in soil.

Introduction

Did you know that the soil beneath your feet is full of life? Healthy soil is teeming with life and full of micro-invertebrates, or tiny animals without skeletons. Some examples of soil-dwelling invertebrates are worms (called annelids and nematodes), and bugs (called arthropods). Here are some interesting facts about soil-dwelling arthropods from Andrew Moldenke at Oregon State University (Moldenke, A.R., 2000):

• Many bugs, known as arthropods, make their home in the soil. They get their name from their jointed (arthros) legs (podos). Arthropods are invertebrates; that is, they have no backbone, and rely instead on an external covering called an exoskeleton.
• Arthropods range in size, from microscopic to several inches in length. They include insects, such as springtails, beetles, and ants; crustaceans, such as sowbugs; arachnids, such as spiders and mites; myriapods, such as centipedes and millipedes; and scorpions.
• Nearly every soil is home to many different arthropod species. Certain row-crop soils, like the soil that corn and soybeans are grown in, contain several dozen species of arthropods in a square mile. Several thousand different species might live in a square mile of forest soil.
• Arthropods can be grouped as shredders, predators, herbivores, and fungal-feeders, based on their functions in soil. Most soil-dwelling arthropods eat fungi, worms, or other arthropods. Root-feeders and dead-plant shredders are less abundant. As they feed, arthropods aerate and mix the soil, regulate the population size of other soil organisms, and shred organic material.

Many soil-dwelling arthropods are very small, even microscopic, and can easily be missed unless you know how to catch them! Very small arthropods are called micro-arthropods. One way to catch soil-dwelling micro-arthropods is to construct a Berlese funnel using a funnel, some screen material, and a dark jar filled with a preservative liquid like ethyl alcohol or antifreeze. Soil is scooped into the funnel and the funnel is placed over the dark jar in a well-lit location. As the micro-arthropods burrow deep into the soil to avoid the light,they fall into the jar filled with preservative. Then you can look at them all with a magnifying glass and marvel at the diversity of soil-dwelling micro-arthropods!

A Berlese Funnel consists of: A) liquid for conservation (alcohol at 70°), B) bottle, C) filter, D) ground, litter, leaves, etc., E) funnel, F) heat, G) source of heat. (Wikipedia Contributors, 2007; Image Credit: Valerie Chansigaud)	"The 200 species of mites in this microscope view were extracted from one square foot of the top two inches of forest litter and soil. Mites are poorly studied, but enormously significant for nutrient release in the soil." (Moldenke, A.R., 2000; Image Credit: Val Behan-Pelletier, Agriculture and Agri-Food Canada)

In this experiment, you will construct your own Berlese funnel and use it to catch micro-arthropods from your garden soil. You will collect micro-arthropod samples from soils at different locations around your home and garden. Will the number of micro-arthropods in each sample correlate with the soil quality at each site?

Terms, Concepts, and Questions to Start Background Research

To do this type of experiment, you should know what the following terms mean. Have an adult help you search the Internet or take you to your local library to find out more!

• Soil
• Micro-invertebrate
• Micro-arthropod
• Berlese funnel
• Organism

• What types of organisms live in the soil?
• What do micro-arthropods look like under a magnifying lens?
• How does a Berlese funnel allow you to collect micro-invertebrates from the soil?

Bibliography

• Read about Antonio Berlese, the inventor of the Berlese funnel on Wikipedia:
  Wikipedia contributors. (2007). Antonio Berlese. Wikipedia, The Free Encyclopedia. Retrieved December 6, 2007 from http://en.wikipedia.org/w/index.php?title=Antonio_Berlese&oldid=156925876
• This is an excellent resource about soil biology and the lives of arthropods that live in the soil:
  Moldenke, A.R. (2000). The Soil Biology Primer: Chapter 7: Arthropods. Natural Resources Conservation Service (NRCS), United States Department of Agriculture (USDA). Retrieved December 6, 2007 from http://soils.usda.gov/sqi/concepts/soil_biology/arthropods.html
• Here is another good soil resource that explains the importance of macrofauna, mesofauna, and microfauna to soil health:
  TFREC. (2004). Soil Fauna. Tree Fruit Research and Extension Center (TFREC), Washington State University (WSU). Retrieved December 6, 2007 from http://soils.tfrec.wsu.edu/mg/fauna.htm

Materials and Equipment

• One-gallon plastic milk container (1, empty)
• Empty jelly jar (or a one-pint Mason jar) with a tight lid
• A straight stick or rod (about 25 cm long)
• 1/4" mesh hardware cloth or aluminum window screen (15x15-cm piece)
• Scissors
• Masking tape or duct tape
• Black construction paper
• Rubbing alcohol (ethyl), available at drug stores
• Lamp
• Soil samples from around your home
• Magnifying lens or Loupe

Experimental Procedure

1. Tape the sheet of black construction paper around the outside of the Mason jar.
2. Pour alcohol into the Mason jar to a depth of 1-2 cm.
3. Cut the bottom out of the milk jug.
4. Tape the stick to the handle of the milk jug so it is just long enough to reach the outside bottom of the Mason jar when it is placed on top of it to make the funnel.
5. Use the hardware cloth to create a basket in the wide end of the funnel. To do this, place the hardware cloth over the open top, bending the edges of the cloth over the edge of the plastic container. You can use tape to secure the edges. Make sure you are creating a pit/basket in the middle that is deep enough to hold all your soil and gives the animals enough room to burrow down. If you are using window screen, fit it the same way, but cut numerous slits into the screen first so that larger animals can crawl through, down into the funnel.
6. Collect several handfuls of soil from different locations around your home. Be sure to label where the sample was taken from and include a date. You will use the Berlese funnel one sample at a time to collect micro-invertebrates. Or you could make several funnels, one per sample. If you have a cut or wound, you should wear latex or rubber gloves when collecting and working with the soil.
7. Put the soil sample, including leaf litter, on top of the wire mesh.
8. Carefully set the funnel on top of the Mason jar and tape the stick to the jar so it won't tip over.
9. Leave the funnel in a warm, quiet place where it won't be disturbed.
10. Set a lamp over the funnel, but keep the light bulb at least 10 cm away from the funnel.
11. Look at your samples with a magnifying lens or Loupe. What differences do you see?
12. Count the number of micro-arthropods and other fauna in each sample. Record your results in a data table:

    Sample Location	Number of Micro-fauna	Other Interesting Observations
    Vegetable Garden
    Lawn
    Pathway
    Etc...

13. Which samples had the most fauna? The least? What conclusion does this lead you to about the quality of soils around your home?

Variations

• Collect samples from other areas (your school, a park, etc...) and compare. What do you notice?
• Try and separate the organisms in each sample into similar looking fauna. How many different types of organisms do you think you have? Do any of them look familiar?
• Advanced students can try to identify some of the insects and fauna in the samples. Do different samples contain the same types of fauna?

• For more science project ideas in this area of science, see Environmental Science Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2008-02-20 14:00:00