Clove Oil

Clove Oil: An Anesthetic to Knock Out Zooplankton?

Everyone has been frustrated by having a particular specimen swim out of the field of view or by having another specimen knock the one of interest. Often simple chilling of samples will slow zooplankton sufficiently to allow a good look. If this fails, a variety of anesthetics are variously effective on specific taxa. Unfortunately, many are expensive, difficult to find, or have significant safety concerns. Now we can recommend clove oil as an effective, non-toxic, and inexpensive anesthetic for both fishes and invertebrates.

Try adding clove oil dropwise to your sample. Wait a few minutes between drops to assess effectiveness. Addition of a small amount of ethanol will aid mixing. Hopefully, a number of you will try this method and then share your impressions with us to include on this web site.

Where to Find Clove Oil.
Clove oil as found in “toothache drops” may be available at local or on-line pharmacies and is relatively inexpensive. The amount used may need to be increased depending on the concentration of clove oil found as an active ingredient in the medication. Also, eugenol, the active ingredient in clove oil (80-90%), may be purchased from chemical suppliers. If clove oil is unavailable at the pharmacy, other toothache remedies may work, but we have not tested them.

SAFETY NOTE. May cause skin irritation or irritate eyes. Use standard lab safety precautions.

Submitted by: Bill Johnson, Goucher College, Towson, MD. June 2, 2005


Mighty Fine Dissecting Needles—Make ‘em yourself

When standard dissecting needles and even fine forcepts are too big, ”Minutien” pins mounted on balsa wood handles provide an inexpensive way to make finer needles for manipulating zooplankton.


Minutien pins. Small stainless steel Minutien Pins are used by entomologists for mounting fine specimens and are available from Carolina Biological

Balsa Sticks, 1/8″ square: Available in local hobby shops that carry supplies for model airplane construction.


Use pliers to push the blunt end of the pins into 4-6” lengths of 1/8” square balsa wood sticks. Gluing is optional.


Submitted by: Bill Johnson, Goucher College, Towson, MD. June 2, 2005