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In this lab, students use a Berlese funnel to take samples of soil-dwelling animals, and then compare the numbers and kinds of organisms collected from different habitats.
lamps 40-watt incandescent bulbs
support stand for each lamp
70% isopropyl alcohol (972924) (or other alcohol)
trowel(s)
plastic bags, 15 cm × 15 cm × 5 cm or larger (for holding samples) (713093)
index cards
newspaper or paper towels
dissecting microscopes (591815)
Isopropyl alcohol evaporates rapidly, and if the collection vial dries out, specimens can be lost. This can be prevented by adding a few drops of glycerol (865530) per 100 mL of isopropyl alcohol. Hand lenses can be substituted for dissecting microscopes. Most of the specimens collected will be white. A circle of black paper placed on the stage of the dissecting scope will make the specimens show up better for counting. Probes for moving the specimens can be constructed from toothpicks and hairs. Attach a hair to a toothpick with nail polish or fast-drying glue. Cut the hair so that it extends about 5 mm past the tip of the toothpick.
Ensure that students understand and adhere to safe laboratory practices when performing any activity in the classroom or lab. Demonstrate the protocol for correctly using the instruments and materials necessary to complete the activities, and emphasize the importance of proper usage. Use personal protective equipment such as safety glasses or goggles, gloves, and aprons when appropriate. Model proper laboratory safety practices for your students and require them to adhere to all laboratory safety rules.
This activity requires the use of electricity and an incandescent bulb that can become very hot. A 40-watt bulb is recommended. In no case should the wattage exceed 60.
Students can work singly or in groups of 4. If performed by a single student or a single group, it is best to provide two funnel setups, so that two habitats can be sampled concurrently. If this is not possible, refrigerate the first sample while the second is being extracted.
Set up a workstation for each Berlese funnel. In addition to a Berlese funnel and ringstand, each station should be supplied with sheets of newspaper or paper towels, alcohol, cheesecloth, a lamp equipped with a 40-watt incandescent bulb, and a support stand or other method of suspending the lamp above the funnel.
For sample collection, each group will need a trowel, a metric ruler, an index card (and a writing instrument), and a large plastic bag capable of holding a sample sized 15 cm × 15 cm × 5 cm.
Optional: Nematodes are common in most soils but are greatly underrepresented in extractions done with a Berlese funnel. A simple method of extracting nematodes is to set a circle of mesh (e.g., a metal window screen) into a bowl, wrap a soil sample in cheesecloth, and set this on the mesh. Add springwater or dechlorinated tap water to the bowl until the mesh is barely covered. Let the bowl sit for 1–3 days. Nematodes and other organisms will drop from the soil into the water, where they can be collected and examined.
A dichotomous key (“Identification Key for Soil Animals”) is provided with the Student LabSheet. However, an Internet search will yield a variety of more-detailed identification keys, if one is desired.
Answers will vary depending on the data collected. The following sample data and answers are based on samples taken from a hardwood forest and a pine forest.
Data Table of Soil Animals Collected from Habitat 1: Hardwood Forest
Animal | Count (Absolute Abundance) | Relative Abundance |
Ant | 1 | 0.02 |
Diplura | 1 | 0.02 |
Mite | 41 | 0.77 |
Spider | 1 | 0.02 |
Springtail | 8 | 0.15 |
Unidentified A | 1 | 0.02 |
Total Counted | 53 |
Data Table of Soil Animals Collected from Habitat 2: Pine Forest
Animal | Count (Absolute Abundance) | Relative Abundance |
Ant | 1 | 0.04 |
Centipede | 1 | 0.04 |
Mite | 21 | 0.84 |
Unidentified A | 2 | 0.08 |
Total Counted | 25 |
Bird | Count (Absolute Abundance) |
Cardinal | 4 |
Robin | 8 |
Song Sparrow | 5 |
Towhee | 2 |
Total Counted | 19 |