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Life cycle

The acanthocephalans are one of the smallest and least diverse metazoan parasites, yet they can be found on all continents and in a variety of environments, including sea and fresh water (Kennedy 2006). They are thorn-headed parasitic worms whose life cycle requires two hosts. They begin their development when an intermediate host (typically an isopod, amphipod, or an insect) inadvertently consumes the acanthocephalan eggs . Once inside, the parasite grows in the host’s alimentary canal, avoiding significant mechanical damage to the host’s body. Once the parasite reaches the cystacanth stage, it needs to transfer to a new, definitive, vertebrate (generally a bird or a fish), in order to be able to reproduce and complete its life cycle. Inside the definitive host, they reproduce sexually and the eggs are released with the host’s feces. The transfer requires that the definitive host consume the intermediate host (Bierbower et al 2007, Benesh et al 2008, Moore 1983, Kennedy 2006).

The cystacanths do not leave such a crucial step in their life cycle to fate and work to modify the behavior and physiology of the invertebrate so as to maximally increase their chance of being eaten by the definitive host (Bakker 1997). The parasite makes the intermediate host more vulnerable to predation by variety of ways such as by decreasing its stamina, making it highly conspicuous, making it disoriented, and inversing its responses to environmental stimuli that indicate definitive host presence (Moore 1983). For acanthocephalans like Pomphorhynchus laevis, the level of behavior manipulation is higher if two parasites infect an individual rather than one, but the manipulation level does not increase for higher number of parasites. They cystacanths also have to be of the right age during transmission, i.e. older than 30 days. If they infect the definitive host too early, they might not be able to remain in the intestine. On the other hand, they usually do not survive longer than a year if not passed on to the next host (Kennedy 2006). Behavioral changes are more intense if the host is infected with older cystacanths (Franceschi 2008), reflecting the urgency to move on.

an Acanthocephalan life cycle diagram
Acanthocephalan life cycle (Moore 1983, Kennedy 2006)

The size of the parasite population may follow an annual cycle (Brattey 1988). For instance, adult Acanthocephalus lucii living in Scotland are most abundant in late spring and summer, decline in numbers during autumn, and reach a minimum during winter. There is only one generation per year and there is a continual flow of parasites through the population of its final host, the European perch, Perca flaviatilis. The cycle may be driven by seasonal changes in the number of infective larvae, host’s resistance to infection, or host feeding behavior (Brattey 1988).

Parasite-host dynamics

Along with serving as a mode of transmission to the final host, the intermediate host’s other role in the parasite’s life is as a source of nutrients. It is in the parasite’s interest to consume as many nutrients (i.e. eat as much of the host) as possible in order to grow and develop, but it is also in its interests to keep the host alive and fit, in order to escape predation until the parasite is ready to be transmitted. Thus, the parasite must find an optimum level of exploitation that maximizes growth and also maximizes the chances eventual of predation on the host (Benesh 2000). One method of dealing with this conflict is to infect a larger host in the first place, so that there are more nutrients to consume and more room to grow (Hasu 2007).

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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