VI. Widgets

Purpose of tool:

This tool allows students to gently touch, nudge, or push small aquatic or terrestrial organisms, such as mollusks, annelid, crustacean, insect, etc. Widgets are particularly useful for testing tactile sensitivity of specific parts of small, soft-bodied organisms, such as the end of a worm or the tentacle of a snail. These probes deliver touch stimuli of consistent strength, while minimizing injury or insult to organisms. Also, they are extremely useful for selecting and transferring dry microfossils (see: http://www.eeob.iastate.edu/faculty/DrewesC/htdocs/micFOSS-widgFIN.jpg) 

Required Materials:

Long, slender rubber bands for widget tips [For thick widget tips: Universal or Plymouth brand #19 rubber bands; 3-1/2 in x1/16 in x1/32 in] [For thin widget tips, two options exist: (1) Stretch-Rite Metallic Elastic Cord. This product is sold at many fabric stores and contains eight slender white bands within the metallic braid; (2) Rubber legs colored elastic strands are sold at fly fishing supply stores. Rubber legs have exceptional elasticity properties.]

Wooden applicator stick

Heavy scissors or side cutters

Small disposable pipet tips (e.g., 10 microliter size)

Small ruler

Super glue (quick-drying cyanoacrylate glue)

Assembly and use of this tool:

1. Firmly insert one end of an applicator stick into a small, disposable pipet tip (Fig. 13). 

2. Use heavy scissors to cut off the pipet tip just beyond the inserted end of the stick.

3. Obtain multiple lengths of elastic band, each about 3-4 cm in length. [Note: If thin rubber strands are obtained from braided metallic elastic bands, then it will be necessary to remove the metallic braid and tease apart the individual strands of rubber band that compose the core of the band.]

4. Insert one end of an elastic band into the trimmed pipet tip, with about 1 cm of band extending beyond the narrow end of the pipet tip, as shown in Fig 13.

5. Insert one end of an applicator stick into the large end of the pipet tip. Firmly wedge the stick against the elastic band and the pipet tip, making sure that at least 1 cm of elastic band still extends beyond the pipet tip.

6. Apply a small drop of super glue into the large end of the pipet tip. The glue should contact the rubber band and wooden stick within the pipet tip. Allow the assembly to dry.

7. Use a scissors to trim off the rubber band, as needed.

Figure 13. Assembly steps for making widgets.

Figure 14. Examples of three widgets. The loop widget in the center is particularly useful for initiating helical swimming and body reversal in blackworms (Lumbriculus).

8. NOTE: Many other widget configurations are possible. Some are shown in Fig. 14. Thin-tipped widgets may be made from very slender rubber band material, or even human hair. Looped widget tips are very useful for stimulating tail or head segments of blackworms (Lumbriculus). Such stimulation reliably initiates helical swimming and body reversal behaviors in these worms, respectively (Drewes and Cain, 1999)

[Total cost per widget is less than 5 cents.  Assembly time is less than 5 min/unit.]