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Define symbiont (symbiote)
Any organism spending a portion or all of its life intimately associated with another organism of different species
What are the 4 categories of symbiosis with a description and example of each. Include specific terminology for each member if necessary.
- *note- overlapping is common
- Phoresis: the larger host carries the smaller phoront. Neither is physiologically dependent.
- ex- bacteria on legs of fly, fungi on aquatic arthropods, barnacles on sharks
- Commensalism: The commensal benefits, and the host is neither harmed nor benefits
- ex- Hermit crabs carry sea anemones on their borrowed shells, cleaner shrimp, clownfish in sea anemones
- Mutualism: both partners (mutuals) benefit and depend on eachother physiologically
- ex- Termites and flagellates
- ex- aquatic cleaners set up cleaning stations and attract large cooperating hosts
- ex- Corals and algae (zooxanthellae)
- Parasitism: the parasite lives at the expense of the host
- Dependence can be temporary (feeding) or determinant (tapeworm)
Obligate vs facultative parasites
- Obligate: physiologically dependent on host and cannot survive if kept isolation (most parasites)
- Facultative: mostly free living and not normally parasitic but can become so if accidentally encountered (few parasites)
- ex- Naegleria and Micronema
Define incidental parasite. Give an example.
- When a parasite enters or attaches to body of host other than its normal one. (AKA accidental parasite)
- ex- bird flukes can live temporarily in the skin of humans (swimmer's itch)
Define: ectoparasite, endoparasite, definitive host, intermediate host, paratenic host
- Ectoparasite: if the parasite lives on the surface of its host or superficially embedded in the body surface
- ex- tick, leech, fleas
- Endoparasite: if the parasite lives internally (alimentary tract, liver, lungs, and urinary bladder)
- ex- tapeworms, trematodes, etc
- Definitive host: parasite attains sexual maturity and reproduce (AKA primary host)
- Intermediate host: some development of the parasite occurs but in which id does not reach maturity (AKA secondary host)
- ex-snails, insects, etc
- Paratenic host: host is not required for the completion of the parasite's life cycle but utilized as a temporary refuge (vehicle) for reaching the definitive host (AKA transfer host)
- ex- the thorny-headed worm uses an insect as the parantenic host (shrew) eats the intermediate host (insect) so that it can be transferred to the definitive host (owl)
- *NOTE- no development occurs
Define reservoir host, sylvatic reservoir host, domestic reservoir host, zoonosis, vector, hyperparasitism, verminous intoxication. Give an example for each
- Reservoir host: infected animals that serve as a source of human parasites without typically being symptomatic
- ex- filarial worm transmitted to humans by mosquito from monkeys (sylvatic) and cats (domestic)
- Sylvatic reservoir host: wild animal
- Domestic reservoir host: domestic animal
- Zoonosis: disease of humans caused by pathogenic parasite found in vertebrate animals (person to person transmission does not typically occur)
- ex- Trichinella spiralis found in a variety of reservoirs (esp. pigs) and humans are infected by eating meat.
- Vector: anything (living or non-living) that serves as a carrier of parasites
- ex- bug, fish, water, air
- Hyperparasitism: parasites hosting additional parasites
- ex- Plasmodium in a mosquito
- Verminous intoxication: poisoning of the host with toxic metabolic products
How can parasites harm hosts?
- Mechanical injury
- Derviting nutritive substances such as blood, lymph, cytoplasm, digesting tissue fluid and host food
- Poisoning the host with toxic metabolic products (verminous intoxication) leading to lethargy, bloating, hunger, allergies, gas, unclear thinking, weightloss, etc
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