BIOL2712 Study Guide - Final Guide: Trematoda, Cutaneous Larva Migrans, Small Intestine
25 Jun 2018
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Parasitic Worms
Definitions
Parasitism
oInteraction in which one organism, the parasite, lives at the expense of
another organism, the host
oDestructive symbiosis
Ectoparasite
oParasite which lives on the outside of the host
Endoparasite
oParasite which lives within the host
Parasites
oLive in contact with host at some stage of their life cycle
oHarm their host (rarely kill it)
oObtain their nourishment from host
oSmaller than host
oCause disease outbreak in host only if hyperinfestation
Advantages of being an endoparasite
Food supple constant and unlimited, pre-digested
No predators within host
Protection from external environmental changes
oLong life
Challenges of being an endoparasite
Get past the teeth
Avoid being digested
End up in the right tissue
Host reaction to parasite
oImmune response
oInflammation
Adaptions
Parasitic life mode
oLife cycle
oStructural
Morphological adaptions
oAttachment
Hooks, suckers, spines, claws
Also used to pierce hosts
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Nutrition
Obtained from host
Nutrient uptake through epidermis
Gut degenerated
Less enzymes
Nervous System
Reduced
Sensory organs
Reduced
Reproduction
Replication of reproductive organs
Production of enormous numbers of eggs
Life Cycles
Problems:
oHow to ensure uptake by host
oHow to secure population numbers
oHow to find a mate
oHow can eggs leave host body?
Combination of mobile, resistant and reproductive stages > one hosts:
oIntermediate host(s)
oFinal (definite) host
How to find a mate?
Mostly hermaphrodite
Dwarf males/females
Cysts with male and female parasites
Asexual
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oLarval multiplication
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find more resources at oneclass.com
Document Summary
Parasitism: interaction in which one organism, the parasite, lives at the expense of another organism, the host, destructive symbiosis. Ectoparasite: parasite which lives on the outside of the host. Endoparasite: parasite which lives within the host. Parasites: live in contact with host at some stage of their life cycle, harm their host (rarely kill it, obtain their nourishment from host, smaller than host, cause disease outbreak in host only if hyperinfestation. Protection from external environmental changes: long life. Host reaction to parasite: immune response, inflammation. Combination of mobile, resistant and reproductive stages > one hosts: intermediate host(s, final (definite) host. Entering the host: passive (uptake, active search, drawing attention. Cercaria and metacercaria remain in sporocyst, encysted 12mm length: penetrates tentacle of snail, pulsates rhythmically, colour stripped, parasite induced sail to crawl to edge of leaves. Trematoda adult flukes feed on host tissues and fluids: monogenea. Uptake by eating raw or uncooked fish.
