They can also be consumed in drinking water - they attach to the lining of the nose or throat and eventually make their way down to the lungs, potentially causing suffocation (something that happens routinely with domestic animals in Asia). In regions where leeches are commonly found, they might enter through the orifices of a body (human or other mammal) bathing in infested waters. Leeches are hermaphroditic, but must mate with another leech of the same species to fertilize their eggs, which are then laid in a cocoon on land or in water. They use sharp teeth to attach to their host's skin, but since the leech's saliva contains an anesthetic and an anticoagulant, hosts generally aren't aware they've been bitten until after the critter has moved on. A few species subsist on plant matter but the majority of leeches are parasitic and consume blood. Their most notable characteristics are their suckers, a small one at the mouth-end and a larger one toward the posterior. On average, they range in size from under half an inch to 8 inches long, though the giant Amazon leech grows up to 18" in length. The leech is actually considered a segmented worm, and there are over 650 different species of them, living both on land and in water. Most people have a passing familiarity with the leech - a slimy little invertebrate that attaches itself to a living body and obtains nourishment by sucking its host's blood. Many common ailments were believed to be caused by an excess of blood, and consequently removing some of a person's blood was thought to be efficacious often doctors employed leeches for this purpose. Nimura's biography of Elizabeth and Emily Blackwell, explores the tools 19th-century physicians used to address their patients' needs. This article relates to The Doctors Blackwell
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