Medicinal leech
Scientific name: Hirudo medicinalis
Country: Albania, Armenia, Austria, Azerbaijan, Belarus, Belgium, Bulgaria, Czech Republic, Denmark, Estonia, Finland, France, Georgia, Germany, Greece, Hungary, Ireland, Italy, Kazakhstan, Latvia, Lithuania, Luxembourg, Moldova, Netherlands, Norway, Poland, Portugal, Romania, Russia, Spain, Sweden, Switzerland, Turkey, Ukraine, United Kingdom, Yugoslavia
Continent: Europe, Asia
Diet: Blood of birds, fish, frogs, mammals
Food & feeding: Carnivore
Habitats: Freshwater
Conservation Status: Near Threatened
Relatives: Earthworm, lugworm
Description: Leeches have segmented bodies like an earthworm, but unlike earthworms they are slightly flattened rather than round. They have a sucker at the head and the tail end and the one at the head surrounds the mouth. The mouth contains three jaws that can break the skin of their hosts to suck their blood. Medicinal leeches are greenish brown on their backs with thin red stripes running along the body and paler below. They grow up to 20 cm in length.
Lifestyle: Leeches live in shallow muddy pools and ponds with plenty of waterweeds. When hungry, they attach themselves to a passing animal, break the skin with their jaws, and inject special chemicals that prevent the blood from clotting and reduces any pain. They then suck the blood of the host until they are full, when they withdraw their jaws and drop off into the water. They can consume 15 grams of blood - ten times their own body weight, before they are full, but they only need to feed every six months.
Family & friends: Like slugs, leeches are hermaphrodite, having both male and female parts, but they still need to come together to mate with each other.
Keeping in touch: Little is known about leech communication.
Growing up: After mating, 15-50 eggs are laid in a spongy case or cocoon, above the waterline often under stones. The eggs hatch in 3-5 weeks and the young leeches need two seasons of feeding before they are ready to breed themselves.
Conservation news: The removal of millions of leeches for medical use in the 19th century reduced the numbers of wild leeches dramatically and in the last century, numbers were reduced further due to drainage of the ponds and ditches that they live in. The reduction of plough horses on farms (now replaced by tractors) has also affected leech numbers as horses used to be a favourite source of blood when they went to drink in ponds and ditches.
For over 4000 years, the leech has been a familiar remedy, with Greek and Roman physicians praising the application of this clever invertebrate. In the 19th century leeches were enjoying a golden age. Millions were raised and reared for medical use as their fame as a cure-all ensued.The mid 1800s saw their constant use for local bloodletting. Druggists administered thousands of leeches to patients with anything from gumboils to facial discolouration. Leeches were applied to the mouth and inside of the throat using a leech-glass, although patients frequently swallowed them. Patients were relieved only with a salty drink of water or perhaps the most popular cure-all of the day, a couple of glasses of wine. Sometimes the leech would not drink and then had to be encouraged by some blood or cream smeared at the puncture site or bathed in a warm glass of beer until ready.Once sucking, an average leech would drink its fill in about 15 minutes and consume between 2.5-5.5 grams of blood (half a teaspoon). If the bite failed to stop bleeding after the leech was removed then vinegar, silver nitrate and hot wires were applied. Apart from using the English and Scottish leeches, huge numbers were imported from France, Hungary, the Ukraine, Turkey, Rumania, Russia, Egypt and Algeria. In 1846 in France alone, 30 million leeches were used. Hospitals in both London and Paris required 13 million between them for that single year. America produced their own leeches and one farm sold over a thousand a day everyday. Leeches were also caught from the wild by many interesting ways, including men baiting a muddy ditch or stream with a glass of pig blood, rolling their trousers up and wading into the water. Here they would wait patiently for leeches to adhere themselves to their legs. After a while, back on land the feeding leeches could be stripped off and sold to leech dealers. The leech industry began its decline due to the over collection of the animal and its discredit by the medical profession. By the end of the 19th century the golden age of the leech had passed. Today leeches are bred in captivity in many institutions including Bristol Zoo Gardens. Leeches have found new fame in microsurgery, where doctors require the precision of the leech to drain congested blood from wound sites. Plastic surgeons are particularly grateful for the contribution made by the leech, due to their use in the treatment of difficult grafts and reconstructive surgery.
