Scientists Say Health & Medicine

Scientists Say: Ectoparasite

This is parasite that lives on — not in — another organism

860-header-Male_human_head_louse.gif

This is a human head louse. It’s a type of parasite that can live on a person’s scalp.

Giles San Martin/Wikimedia Commons (CC BY-SA 2.0)

By Bethany Brookshire

Ectoparasite (noun, “ECK-to-PAIR-a-site”)

Like a terrible houseguest, a parasite relies on another organism — one it lives on or in — for its nutrients and gives nothing in return. The parasite benefits, while the host usually suffers in some way. Many parasites, such as tapeworms, live inside the host’s body. But ectoparasites are found outside the host. (“Ecto-“ is from the Greek language, and means “outside.”) Examples include a dog’s fleas and the head lice that spread from kid to kid in the classroom.

In a sentence

Lice and fleas that lived on people were ectoparasites that helped spread the infamous Black Death through Europe.

Check out the full list of Scientists Say here. 

Power Words

More About Power Words

Black Death     A European outbreak of bubonic plague in the Middle Ages that claimed the lives of up to 200 million people throughout a period of about four years. By the time it was over in 1351, between a quarter and half of all European residents had died.

ectoparasite     A parasite such as a flea or louse, which lives outside of its host.  

host      (in biology and medicine) The organism (or environment) in which some other thing resides. Humans may be a temporary host for food-poisoning germs or other infective agents.

organism     Any living thing, from elephants and plants to bacteria and other types of single-celled life.

parasite     An organism that gets benefits from another species, called a host, but doesn’t provide that host any benefits. Classic examples of parasites include ticks, fleas and tapeworms.

About Bethany Brookshire

Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

More Stories from Science News Explores on Health & Medicine

  1. Health & Medicine

    This Indigenous herb may improve therapy for muscle disorder

    By Maria Temming
  2. Artificial Intelligence

    AI-designed proteins target toxins in deadly snake venom

    By Meghan Rosen
  3. Health & Medicine

    2025’s Texas measles outbreak is a lesson in the value of vaccines

    By Tina Hesman Saey
  4. Brain

    Explainer: How our body deals with stress

    By Jennifer Junghans
  5. Brain

    Could the magic of memory manipulation ever become real?

    By Andrea Tamayo
  6. Genetics

    This young biologist looked for links between diet and dyslexia

    By Maria Temming
  7. Plants

    Microbes give plants a way to make ‘meaty’ nutrients

    By Skyler Ware
  8. Health & Medicine

    Can you really die of a broken heart?

    By Bethany Brookshire
Use up and down arrow keys to explore.Use right arrow key to move into the list.Use left arrow key to move back to the parent list.Use tab key to enter the current list item.Use escape to exit the menu.Use the Shift key with the Tab key to tab back to the search input.