Tapeworm

• What is a tapeworm?

  An endoparasite of the small intestine
• How are tapeworms passed on from host to host?

  Primary host: human -> faeces containing fertilised tapeworm eggs -> secondary host: pigs -> faeces is spread in grass and eaten by pigs -> cysts in undercooked pork are eaten and passed onto humans again
• What are the adaptations of the tapeworm?

  -scolex (head) has hooks and suckers: attaches to small intestine wall and doesn't get removed by peristalsis

  -body is long and thin: large SA and short diffusion pathway: to absorb more nutrients

  -no digestive system: nutrients absorbed are end products of digestion

  -has a cuticle and anti-enzymes: allows it to resists digestion by host

  -hermaphrodites: can self-fertilise

  -produces lots of embryos: increases chance of life cycle continuing
• How do tapeworms get passed from pigs to humans?

  Egg contaminated vegetation is ingested by pig -> eggs hatch into larvae and infect the pig's muscle tissue -> larval cysts in muscle tissue -> undercooked/raw food contains cysts -> humans ingest contaminated food
• The secretion of mucus provides protection from digestive enzymes, and alkaline secretions neutralises acid to protect the tapeworm
• How is the tapeworm adapted to obtain its nutrients?

  -attaches to gut wall by hooks and suckers

  -thin body creates a short diffusion pathway

  -large surface area to volume ratio
• Why are tapeworms found in the small intestine?

  -they lack a digestive system

  -the small intestine contains the end products of digestion, so nutrients can simply diffuse across the body surface