Why do we collect parasites? Pickled parasites in the vast collections of the U.S. Department of Agriculture, which are now managed by the Smithsonian. (Photo bottom left): Parasitic horsehair (Nematomorpha) (National Museum of Natural History/Anna Phillips)
Why do we collect parasites?
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Who would keep a collection of parasites?
 
Believe it or not, the United States government has been collecting parasites for a hundred years. The collection recently was acquired by the Smithsonian. It now numbers more than 20 million parasites. We keep parasites because they are a priority for research related to our well-being.

Parasites cause many diseases. Endoparasites, which can live inside your body, include flatworms such as tapeworms or flukes, as well as tiny animals of various types that cause infections. Even parasites that live on the surface of your body (ectoparasites) may cause infections by giving rides to other organisms.  Ticks give rides to Lyme disease bacteria, which cause as many as 25,000 infections per year in the U.S. alone.
 
Ironically, parasites are also used for medical treatments. Thanks to natural anticoagulants in their spit, leeches can keep blood flowing into reattached body parts that have been severed in accidents.

However, the importance of parasites goes way beyond their roles in disease. Research on parasites has been led by medical concerns, but parasites are also players to be reckoned with in the ecosystems we depend on. Recent studies along the California coast and elsewhere have revealed that the biomass (weight) of all the parasites in an ecosystem may be higher than the biomass of all the top predators. While parasites tend to be small, there are lots and lots of them around!

By definition, a parasite lives in or on a "host," whether a plant, a mammal like a human, or other animals like crabs. Parasites take resources from their hosts without giving back. They usually don't kill their hosts. Like bad house guests, they may affect how their hosts behave. The close linkage they have with hosts makes parasites relevant for how entire ecosystems function and respond to change. Parasites are too prevalent to be ignored.
 
Learn about how scientists use museum collections to study the many associations between parasites and their hosts. Watch the live "Smithsonian Science How" webcast on Thursday, May 19, 2016. It is titled, "Living Together: Parasites and Hosts" (airs at 11 a.m. and 2 p.m. EDT on the Q?rius website). Parasitologist Dr. Anna Phillips will discuss and answer questions live from the National Museum of Natural History. Get teaching resources to use with the webcast.

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CRITICAL THINKING QUESTION
How can tiny parasites outweigh predators?
Write your answers in the comments section below


COMMENTS (19)
  • collinf-2-bar
    5/12/2016 - 12:20 p.m.

    Tiny parasites outweigh predators because there are so many of them. "Recent studies along the California coast and elsewhere have revealed that the biomass (weight) of all the parasites in an ecosystem may be higher than the biomass of all the top predators. While parasites tend to be small, there are lots and lots of them around!"

    I found this article interesting because parasites interest me.

  • jacks-6-bar
    5/12/2016 - 06:35 p.m.

    Tiny parasites can outweigh predators because of their incredible numbers, despite their size, and their protective refuge. The article states: "[The collection of U.S. parasites] now [number] more than 20 million parasites." This incredible number simply represents the statistics of parasites in the United State's captivity, and disregards other countries, let alone the ones that live in the wild. Though 20 million is a lot of organisms, it is far from the total amount of parasites in the world living. Though their size limits their biomass, their total numbers are so profoundly significant, large, and even unimaginable that they tower above the biomass of the leading predators, from specific areas or the world.
    Another reason the parasites may outweigh the biomass of leading predators is that they aren't exposed to much of anything to kill them, compared to other organisms. The article states: "By definition, a parasite lives in or on a 'host,' whether a plant, a mammal like a human, or other animals like crabs." Since parasites like to spend most of their lives in a host/hosts, they typically don't see many possible, major predators; they are within the shell of an organism, feeding, breeding, and flourishing, with no opposition (since most other organisms, especially predators, cannot enter any host as parasites do). Though other animals can devour the host, the parasites usually use that as the host (if not chomped/boiled alive). Also, they inhabit humans constantly, high above the food chain. With this easy development and prosperity for the parasites and predators more at risk, though tiny, the parasites could outweigh their biomass.
    I found the article quite interesting; I did not know parasites had such a profound significance, from society to the population's entire.

  • aidanp-1-bar
    5/12/2016 - 07:16 p.m.

    Parasites may outweigh the predators because there are so many parasites compared to predators. Even though predators are usually the biggest animals, parasites have thousands of themselves, many living in the predators themselves. On paragraph 5 it says "Recent studies along the California coast and elsewhere have revealed that the biomass (weight) of all the parasites in an ecosystem may be higher than the biomass of all the top predators."

    I liked this article because it was interesting.

  • caitlynk-2-bar
    5/12/2016 - 07:26 p.m.

    A tiny parasite can outweigh a predator because "they may affect how their hosts behave. The close linkage they have with hosts makes parasites relevant for how entire ecosystems function and respond to change." A predator can affect one animal that they are hunting, but parasites can affect an entire ecosystem. This article was interesting because it is weird that the thing that is affecting the way we live is used to heal us. This article surprised me because it is crazy that there are over 20 million parasites.

  • audreyv-4-bar
    5/12/2016 - 08:47 p.m.

    Parasites can outweigh their predators by bringing disease and infection to them, without the predator knowing. Some parasites can also live inside your body, which makes it more difficult for the predator get rid of. Diseases that parasites can bring to your body, can vary; and become extremely dangerous to your health.

    I found this article interesting, because I never knew how a parasite would affect you so drastically.

  • samuelh-3-bar
    5/12/2016 - 10:39 p.m.

    Parasites outweigh predators, because there are many more them in the ecosystem than there are predators.

  • maxwellc-3-bar
    5/12/2016 - 11:23 p.m.

    Tiny parasites can outweigh predators because the total weight of all parasites in an ecosystem is possibly more than the weight of the major predators. In the text, it says, "Recent studies along the California coast and elsewhere have revealed that the biomass (weight) of all the parasites in an ecosystem may be higher than the biomass of all the top predators. While parasites tend to be small, there are lots and lots of them around! I do not completely understand this and how it relates to medical science, but it seems like it would be important for scientists to gain more understanding about.

  • lucasl-3-bar
    5/12/2016 - 11:59 p.m.

    The tiny parasites can "outweigh" predators, as stated by the article, because the biosphere can accommodate for so many more of them. For example, in every ecosystem, a delicate balance of energy transference is necessary to maintain the environment. The small parasites, such as leeches and tapeworms, can live in massive numbers off of relatively few hosts. As a result, their carrying capacity is larger because each organism consumes little resources. Thus, the ecosystem can carry many more parasites than predators. It is interesting how these parasites, despite surviving by attacking other organisms, can help humans. Between medical uses and studies (such as in the case of leeches) and maintaining the world's biosphere, the parasites inadvertently help (as well as harm) other populations.

  • shaelyng-ver
    5/13/2016 - 08:36 a.m.

    I never knew that leeches could keep the blood flowing in severed human parts, that is amazing.

  • michaelm1-ver
    5/13/2016 - 08:56 a.m.

    The parasites could infect many more predators, to live in them.

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