Chitons

Below are examples of chitons you can find without much effort in northern Oregon’s exposed rocky intertidal. I don’t flip rocks, so these are the just chitons that don’t mind some daylight exposure. Even with this limited set, identification is a challenge for me. I list some of my favorite field guides and identification resources at the bottom of this page. I have relied on them, but any identification errors are mine.

Organization and common names are my choice. I refer to WoRMS for scientific names, and I learn a ton by browsing the natural history riches in Kozloff (1993). All photos are from northern Oregon unless otherwise noted in the caption.

Tonicella, lined chiton

I’m fairly certain these are all T. lineata, but there are other, similar lined chitons, like T. lokii. It’s worth giving any Tonicella you find a close look. They’re common, but you’ll need to pick a good low tide to find them. Lined chitons are variable, but the variation I’ve noticed is much more limited than what you’ll see in some of the guides.

A pair of lined chitons, *Tonicella*, showing off some color variation

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Katharina tunicata, black leather chiton

Easy to find and easy to identify, Katharina doesn’t try too hard to hide while it waits out low tide. You’ll find it in the open on low intertidal rocks. In daylight, Katharina will sometimes nose into a shadow. There is individual variation, as seen in the photos below, but you won’t mix it up with any other chiton. I say a few words about Katharina in Black Leather Chiton, Katharina tunicata.

*Katharina tunicata*, getting a little shelter from sea cabbage, *Saccharina sessilis*

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And the Mopalias…

Until I learn a little more about the group below, the closest I’m going to get is the genus. I think all of these are Mopalia, but even that is an open question. I’m guessing Mopalia kennerleyi is represented below. Mopalia hindsii, M. muscosa, and M. lignosa are all in the running too. Maybe others. If you have thoughts on any of these, please let me know.