So, please, just relax, pick off the leech and flick it back into the water. Over-reacting to icky creatures imposes these attitudes on future generations. Remember, the attitude you display towards living things affects other people around you. Yet, hysteria still rains on beaches whenever some swimmer finds a leech on some body part. Leech bites are painless, only tiny amounts of blood are withdrawn and chances of any disease transmission are almost non-existent. And there's no real reason to fear their attacks. Yes, they grab onto us and try to suck our blood, but they are just trying to make a living. Leeches are yet another of group of animals suffering from a "bad rap". The natural anticoagulant that leeches produce as they feed also helps prevent clotting that could lead to loss of blow flow to the damaged regions. Leeches are used to draw off excess blood accumulating in the tissues until new veins and capillaries regenerate. In the surgical repair or re-attachment of certain body parts and in skin grafts venous blood flow is often poor at first. While a questionable practice in general, modern medicine has found a valuable use for leeches. This practice was believed to restore the balance of "humours" within the body. Medicinal LeechesĪ common European species of leech ( Hirudo medicinalis) was once widely used medicinally for blood-letting. Commercially sold leeches (usually The Predatory Leech, Nephelopsis obscura) are harvested from the wild (as are commercially sold Night Crawlers) and in some cases concerns have been raised of over-harvest of local populations. There isn't a current source of information on the overall economic value of leeches to economies in North America, but older references suggest that US states like Minnesota have leech industries that exceed several million dollars annually. A dozen large leeches could cost you three bucks or more. Leeches don't have it all their own way, they're just part of the food chain.Īs any fisher knows, leeches are a popular live bait to use when angling. And lots of other critters will make a meal out of leeches: fish, turtles, shore birds, herons, etc. Some leech species eat other tissues on their prey, some are carrion feeders and some swallow small invertebrates whole. A large blood meal can last a leech for many months. When the leech has filled its crop with blood it releases its suckers and falls off. Large volumes of blood, up to several times the weight of the leech, can be stored in a crop (a widening of the alimentary canal) before digestion begins. Razor sharp blades or beaks in the mouth cut a slot through which blood flows aided by anticoagulants and anesthetics to dull sensations at the wound. Blood-sucking leeches are ambush predators that wait for larger animals to swim by, or move close in the case of terrestrial species, then they grab on to their prey. Watch the video below of a leech "inch-worming" along my hand:įood for most species of leeches is the blood of other animals they are "hematophagous". Leeches get around by swimming in an undulating fashion, like a snake on its side, or by attaching and re-attaching their suckers in an inch-worm fashion. The resulting fertilized eggs are kept in a mucous cocoon which may be kept attached to the underside of the body or deposited in the environment. Two individuals will align themselves and inject each other with sperm. They are hermaphrodites, possessing both sex organs in each individual, but they must cross-fertilize with another of their species to produce viable offspring. The majority of leeches live in fresh water habitats, but some inhabit salt water environments and some can live in moist terrestrial environments. In North America there are thought to be about 63 species, 24 of which can be found here in Manitoba. There are likely more than 700 species of leeches worldwide. The classification of leeches is as follows.
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