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Scientists at the USGS Western Ecological Research Center study the many ecosystems of the Pacific Southwest. Follow our expeditions and projects through this outreach page, and learn more about your local landscape with our library of Outreach Factsheets and photos. Thanks for joining us!

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The parasitic isopod Nerocila californica inside the mouth of a mullet. --Photographer: UC Santa Barbara
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Parasites: Part of a Complete Ecosystem

Stay in a warm cozy bed all day. Shelter from the elements at all times. A fresh buffet at your doorstep open all hours -- even hooked up directly to your gut.

Yup, life as a parasite is pretty sweet.

Parasitic creatures may get a bad rap, but they are nevertheless living organisms, and often they provide very important functions in a healthy ecosystem.

“About 50 percent of animal diversity is parasites,” says Kevin Lafferty, a lead scientist with the USGS Western Ecological Research Center. Lafferty recently was featured in a Convergence magazine article from UC Santa Barbara, where he serves as an adjunct professor.

“There is as wide a range of life-forms inside a fish as there is in an estuary," Lafferty says. “It’s the most popular lifestyle on earth."

Lafferty and his UCSB colleagues study how parasites might serve as indicators of a healthy ecosystem. Additionally, they're trying to explore how parasites might be driving changes in animal behavior, such as an infested fish that is forced to twitch uncontrollably and expose itself to bird predators.

And, quite possibly, even examples like changes in human behavior or cancer risk after parasite infection.

In many senses, parasites take on similar roles as large predators like wolves and lions -- they feed on and gain energy from organisms very high in the food chain. This makes them unlike other organisms of similar size, which typically feed very low in the food chain.

Armadillidium vulgare, a common garden isopod --Photographer: Courtesy of Franco Folini/WikimediaFor example, compare the Nerocila californica in the photo above (happily inside a mullet's mouth) with an ordinary garden pill bug (right). Both are types of small isopods, but one saps energy from a large fish, while the other forages in the dirt for decaying scraps

Clearly, there is a strong case for considering parasitic organisms, their impacts and their functions when trying to survey and understand our ecosystems, food webs and habitats.

“We’d like to see full integration of parasites into ecology as a discipline,” Lafferty says in the Convergence interview. “Most ecologists stop at the outside of the organism.”

Read more about Lafferty's work here.

-- Ben Young Landis

Top Image: A Nerocila californica isopod living inside a mullet's mouth. Image courtesy of UCSB.

Middle Image:
Armadillidium vulgare is a common garden isopod. Image via Wikimedia/Franco Folini

The parasitic isopod Nerocila californica inside the mouth of a mullet. --Photographer: UC Santa Barbara

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