Week 1 - Parasites and Parasitism Flashcards
What is the OED definition of parasitism?
The state of living on, or at the expense of another organism (host).
What is the elaborated definition of parasitism?
A parasite…
- has a metabolic commitment to its host.
- has evolved morphological and physiological adaptations to living in, or on it.
- has the potential to decrease host fitness.
What is ‘phoresy’?
Phoresis
When two symbionts are merely ‘travelling’ together. There is no physiological or biochemical dependence on the part of either participant.
Usually one phoront is smaller than the other and is mechanically carried about by its larger companion.
There is no trophic interaction between the two phoronts.
What is ‘symbiosis’?
Symbiosis
Any two organisms living in close association, commonly one living in or on the body of the other, are symbiotic, as contrasted with free living.
What is ‘mutualism’?
Mutualism
This describes a relationship in which both partners benefit from the association. Mutualism is usually obligatory, since in most cases physiological dependence has evolved to such a degree that one mutual cannot survive without the other.
What is ‘commensalism’?
Commensalism
One partner benefits from the association, but the host is neither helped nor harmed. Many commensal relationships involve feeding on leftover or wasted food, not consumed by the host.
What is ‘parasitism’?
Parasitism
A relationship in which one of the participants, the parasite, either harms its host or in some sense lives at the expense of the host.
Parasites may cause mechanical injury, stimulate damaging inflammation or immune response or simply rob the host of nutrition.
What is the difference between an endo- or ectoparasite?
Ectoparasites live on the surface of its host.
Endoparasites live within the host.
What are ‘obligate parasites’?
Most parasites are ‘obligate parasites’. This means they cannot complete their life cycle without spending at least part of the time in a parasitic relationship.
What are ‘facultative parasites’?
Facultative parasites are not normally parasitic but can become so when they are accidentally eaten or enter a wound or other body orifice.
Describe the different trophic interactions of Predators, Parasitoids, Micropredators and Parasite.
A predator always kills and has many hosts.
A parasitoid always kills but has just one host.
A micropredator seldom kills and has many hosts.
A parasite seldom kills but has just one host.
(The border between parasite and micropredator is fuzzy).
Describe ‘Bodo’
Bodo Makes a living in soil, free living. Has two flagella to catch bacteria and eat them. It is a predator (bacteriovore). Closely related to Crithidia
Describe ‘Crithidia’
Crithidia
Has a free-living stage but also is a parasite of the intestine of arthropods.
Has low host specificity (commensal in some spp.)
It is passed in faeces.
Describe ‘Leishmania’
Leishmania
Is a relative or Crithidia, one step further down the lineage.
Transmitted in the saliva of biting insects.
Are an intracellular parasite of vertebrates.
Has no free-living stage.
Host specific (fly and vertebrate).
Describe the different transmissions of the Trypanosomes.
Aquatic trypanosomes are transmitted by leaches and vertebrates through saliva.
South American trypanosomes are transmitted through faeces by arthropods and vertebrates.
African trypanosomes are transmitted via saliva by arthropods and vertebrates.
