Leeches

Phylulm Annelida (segmented worms) Class Hirudinea

• Bloodsucker

Appearance

• Wormlike, flattened and segmented body
• Body stretches and changes length
• Tear-shaped body when contracted and shortened
• Suckers are located on the underside at each end
• The larger sucker is located at the back
• Dark-coloured with bands, stripes or spots

Behavior

• Swims gracefully with an up-an-down dolphin kick
• Generally moves by inching or looping forward end-to-end with its suckers
• The upraised front-end "looks" for a place to attach
• Avoids light
• Found attached to the underside of rocks

Aquatic Habitat

• Warm, still or quiet water
• In vegetation or under rocks
• Unable to attach to silted substrates

Reproduction

• Leeches are hermaphroditic with male and female organs in each individual
• A mating pair lines up so that opposite sex organs are in contact
• Each leech in a mating pair cross-fertilizes and receives sperm from the other leech
• Egg cocoons are rubbery, dark brown discs (1 cm) attached under leaves and rocks
• Up to ten tiny leeches emerge from each cocoon

Feeding Type

• Scavengers, parasites and predators
• Attach with suckers to fish, birds and people
• Microscopic teeth draw blood from victims
• Saliva contains an anaesthetic (so the victim doesn't feel the cut) and an anticoagulant (to keep blood flowing freely)
• Leeches attached to humans can be pulled or scraped off
• Blood is stored in pouches along the digestive tract and may feed the leech for a considerable time

Pollution Tolerance

• Pollution tolerant
• Large numbers may indicate poor water quality