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As winter starts to move in, I found the need to tidy the office. The happy part of that task is handling and reflecting on souvenirs of past outdoor seasons, the relics of outdoor adventures.

In a small bowl of sea shells is a single plate of a mossy chiton.

Mossy chitons are one of several chitons commonly seen in Oregon tidepools. In addition to mossy chitons, tidepoolers also frequently encounter black leather chitons, gumboot chitons, and lined chitons. A couple others, such as hairy chitons and hooded chitons, are less frequently noticed by people.

Chitons (pronounced “ky-tons”) are somewhat flat to lumpy, crawling mollusks armored by eight plates along the back. Gently arched, the plates overlap a little to form a slightly flexible roof. Chiton plates are held in place by a leathery girdle that forms the outside border and covers at least a little of the plates; color of the girdles and the color and shapes of the plates vary by species, as does the amount of the plates exposed.

On the underside of their oval bodies, chitons have a broad, flat foot that grips the surface; their round mouth is at one end of the foot, the anus at the other, slits running along either edge of the foot between mouth and anus house the gills.

Most (but not all) chitons feed on algae or other encrusting life by rasping their food off surfaces with complex tongues studded with large numbers of very tiny, mineral-tipped teeth. Most graze at night, moving around with their broad foot, and hide in protected spots or clamp down during the day.

About 3 inches long, black leather chitons are shiny black lumps with eight matte white spots where the plates peek through. The iron-tipped teeth on the tongues of black leather chitons can wear down stone through eons of rasping.

Our gumboot chitons are the largest in the world, growing up to more than a foot long. The eight plates of gumboot chitons are completely covered by their tough, slightly-warty, brick-red girdle. Entirely smooth and white, their plates are sometimes called “butterfly shells” because of their shapes.

Rather flat and rarely as big as 2 inches long, lined chitons are gorgeous, sporting colorful, fine, zig-zag stripes on the plates. It usually takes some searching to locate a delicate lined chiton; I reliably find them safely tucked in a purple sea urchin pit, usually under the resident sea urchin.

But I think mossy chitons win the uncoveted title of “prettiest when dead” -- which is how the shell ended up in a bowl in my office.

You might not notice a mossy chiton in life. Not quite 3 inches long at the max, the girdles of mossy chitons cover about the outer two thirds of the plates and is upholstered with short, stiff, brownish hairs that look rather like moss. The exposed center third of the plates may be decorated with etched lines, but are often worn and are frequently covered by other life that can quite effectively camouflage it.

When the tide retreats, some mossy chitons clamp down where they are, ending up exposed on the rock until the tide returns. They can clamp down with remarkable strength, but if caught unawares, black oystercatchers and other shorebirds can sometimes pry them off and eat them. Too, wave-tossed logs or people with scuffling feet can dislodge chitons, leaving them vulnerable to other predation or to death by exposure.

With insides removed, the undersides of the mossy chiton plates are exposed, revealing a beautiful turquoise blue.

Now dead, the chiton’s girdle is either devoured or rotted, and the eight wide-V shaped plates disconnect to go separate ways. The single mossy chiton plate in the bowl in my office was found on a sandy beach, washed up there from rocky pools down the shore.

I wonder that I’ll discover in the next cleaning binge…

For information on how you can arrange an exploration of our fascinating natural history, contact Marty at 541-267-4027,, or Questions and comments about local natural history are welcome.


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