I just stumbled upon a video I took of trematodes from Carpinteria Salt Marsh Reserve, a salt marsh in Santa Barbara County in California. These trematodes have multi-host life cycles and their first intermediate host is the California hornsnail (Cerithidea californica). Trematode eggs get into their snails hosts either by being consumed by the snail or by snail-hunting miracidia which hatched from the trematode egg. Once inside the snail, the trematodes castrate their host (how’s that for rude house guests?) and use the energy that the snail would have put towards reproduction on producing more trematodes. Eventually, the trematode is ready to leave the snail as a cercariae and swim off in search of its second host.

I spent a lot of my summer “shedding cercariae”, which means I was recreating the conditions under which parasites decide to leave their snail host. Placing snails under a warm lamp was all it took and the parasites could be seen swimming around in search of their next host. In the video below you’ll see a California horn snail with little white cercariae swimming around it frantically:

If you’re interested in learning more about these trematodes, check out this blog post on how trematode colonies consist of “queens” and “soldiers”. The researchers who did the study are Ryan Hechinger, Armand Kuris, and Alan Wood. Look for upcoming posts on other research done by Ryan and Armand!

One Response to “Swimming cercariae”

  1. Calimecita

    I hate parasites, while at the same time I have to admire their incredible specializations. Also, many years ago, I hated having to learn all those complex cycles, especially in the case of trematodes with 2 or more intermediate hosts.
    But this is fascinating! It’s been quite a few years since I took my last Invertebrates course and I don’t remember learning anything like this, so thanks for this blog entry!

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.


September 1st, 2018

Graduate student position available studying alternative reproductive tactics at BGSU

We seek a graduate student for a newly NSF-funded project examining the life history decisions made by male smallmouth bass. […]

June 14th, 2018

Part of that World

The other day I was singing “Part of your World” from The Little Mermaid, but was changing some of the […]

June 13th, 2018

Parasite manipulation of host behavior in pop culture

I’m going to be giving a talk at the sure-to-be-amazing Zombie Apocalypse Medicine Meeting. The meeting celebrates all things zombie-related, and […]

June 4th, 2017

Soonish giveaway on Goodreads!

Five copies of the advance reader version of Zach and my new book Soonish are up for grabs on Goodreads! Click […]

March 7th, 2017

Soonish: Ten Emerging Technologies That’ll Improve and/or Ruin Everything

Zach and I wrote a book! Soonish: Ten Emerging Technologies That’ll Improve and/or Ruin Everything explores 10 emerging technologies, and discusses the roadblocks […]

January 26th, 2017

Tales from the Crypt: a parasitoid manipulates the behaviour of its parasite host

I have a new paper out with Dr. Scott Egan, Dr. Andrew Forbes, and Sean Liu! The paper is Open Access […]

May 30th, 2016

Postdoc with Dr. Ryan Hechinger (and me!)

We’re looking for a postdoc! See below! —————— Postdoctoral Opportunity with the Marine Biology Research Division at SIO Postdoctoral Scholar […]

May 7th, 2016

Science…sort of Episode 240: Moon Rocks Don’t Glow

I co-hosted an episode of Science…sort of recently. I pasted the show notes below, but you’ll have to head over […]

February 24th, 2016

Books on parasites

I’m often asked by students to suggest books they can read about parasites. Below is a list of books that […]

August 22nd, 2015

Great Adaptations – A kid’s book about evolution

Zach Weinersmith and I contributed to Tiffany Taylor’s children’s book about evolution. Tiffany worked with scientists to create Seuss-style stories […]