Miss Heidi H. Haugen
Adapted from: "Those Amazing Leeches" by Cheryl M. Halton (Dillon Press, Inc.-1989)
"How do you collect and raise leeches?"
Leeches are classified as annelids, or segmented worms. They are
related to earthworms and share many traits. They are found in
shallow ponds, lakes, and marshes. Some leeches have even been found
to live in small desert water holes as well as in antarctic waters.
Most leeches live in water; however, some leeches are amphibious.
Other leeches are called land leeches and live in moist regions around
Although scientists have found many medicinal applications and uses
for leeches, they can be a nuisance. In 1799, soldiers serving under
Napoleon marched from Egypt across the Sinai Peninsula to Syria. They
drank water from any source they could find, including waters
contaminated by leeches. As a result many problems occurred when the
leeches attached to the insides of the soldiers noses, mouths, and
throats. Once attached, the leeches began to gorge on blood and
enlarge. Many of the soldiers died from suffocation due to the
enlarged leeches in the air passages. In addition, other soldiers
died from excessive blood loss.
Leeches are parasites, that is they live off other organisms without
benefiting the host in return.
Where to look for Leeches
Leeches can be found nearly every place there is water. Shallow
ponds, lakes, and marshes are popular leech collecting sites. The
best time for leech collecting is during the spring and summer. Most
leeches are nocturnal and avoid light. Leeches can often be found in
shady areas of ponds or in dark places under rocks, logs, and debris
of the bottom of lakes.
Leeches can be collected by either using a small dip net, or
gently with forceps. Many of the leeches you find are probably
non-bloodsucking varieties. Most leeches, in fact, feed on small
invertebrates such as snails, worms, and insect larvae. There are
other leeches that have been found to eat fish & amphibian eggs, and
feed on decaying matter at the bottom of their water source. Some of
the bloodsucking leeches attach themselves to an organism such as fish
and frogs for food.
If you prefer the easy way to look for leeches you can visit or
order from your local science supply shop. Both Carolina Biological
and Wards carry leeches.
Caring for Leeches
Avoid placing leeches in chlorinated water. Leeches are sensitive to
substances such as chlorine, copper, and other chemicals. Water from
the collection site, spring water, or dechlorinated tap water is
suitable for maintaining an environment for the leeches. Do not used
distilled water alone since its extreme purity can be harmful to the
leeches' metabolic balance. Keep the water clean and cool. Once
the water shows signs of becoming dirty, it should be cleaned. Do not
change the water all at once. When changing the water change only
25%-50%. Sudden temperature changes could harm the leeches. In
addition, keep leeches out of direct sunlight or artificial light
sources because they too can harm the leeches.
A 10 gallon aquarium is ideal for a classroom supply of leeches
(50max). Be sure to secure a top on the tank-leeches can lengthen
their bodies and fit through incredibly small openings. A screen lid
can be purchased at most pet stores. Be sure that the lid secures
tightly on the aquarium. Filling the tank 75% of the way allows for a
barrier in order to prevent leeches from escaping. You can add sand,
small rocks, shells, and plants to your aquarium. By adding rocks and
other items, your display will look natural and provide places for the
leeches to hide.
Feeding your Leeches
Food requirements are different for each type of leech. Leeches do
not eat often. They can thrive for months on a single meal. A few
live water snails a week would make a great meal. Some of the larger
bloodsucking leeches will require a meal from a turtle or frog every
month or two. Other bloodsucking leeches can be given earthworms,
frog eggs, insect larvae, or even raw ground meat every six-months.
Please answer the following on a separate sheet of paper.
- Write a Learning Log on the proper collection and caring methods for leeches.
- Why can't you use water directly from the tap for raising leeches?
- Where are some locations where you might find leeches? Why?
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