<P> Deficiency of digestive enzymes (except exopeptidases), but, more importantly, deficiency of vitamins, B complex for example, in leeches is compensated for by enzymes and vitamins produced by endosymbiotic microflora . In Hirudo medicinalis, these supplementary factors are produced by an obligatory symbiotic relationship with two bacterial species, Aeromonas veronii and a still - uncharacterized Rikenella species . Nonbloodsucking leeches, such as Erpobdella punctata, are host to three bacterial symbionts, Pseudomonas, Aeromonas, and Klebsiella spp . (a slime producer). The bacteria are passed from parent to offspring in the cocoon as it is formed . </P> <P> Leeches are able to display a variety of behaviors that allow them to explore their environments and feed on their hosts . Exploratory behavior includes head movements and body waving . </P> <P> Some leech species prey on small invertebrates, which they swallow whole . To feed on their hosts, leeches use their anterior suckers to connect to hosts for feeding . Once attached, leeches use a combination of mucus and suction to stay attached and secrete an anticoagulant enzyme, hirudin, into the hosts' blood streams . Only certain species of leeches feed on blood, and not all species can bite; 90% of them feed solely on decomposing bodies and open wounds of amphibians, reptiles, waterfowl, fish, and mammals . A leech attaches itself when it bites, and it will stay attached until it becomes full, at which point it falls off to digest . Due to the hirudin secreted, bites may bleed more than a normal wound after the leech is removed . </P> <P> Leech salivae are commonly believed to contain anesthetic compounds to numb the bite area, but this has never been proven . Although morphine - like substances have been found in leeches, they have been found in the neural tissues, not the salivary tissues . They are used by the leeches in modulating their own immunocytes and not for anesthetizing bite areas on their hosts . Depending on the species and size, leech bites can be barely noticeable or they can be fairly painful . </P>

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