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Species at Risk

Seaside Centipede Lichen

Heterodermia sitchensis

What is the seaside centipede lichen?

A close-up of seaside centipede lichen.
The tiny seaside centipede lichen lives only in the Pacific Northwest.
© Anna Roberts

This rare lichen of the Pacific Northwest was discovered only two decades ago, in the mid-1980s.

The seaside centipede lichen is tiny-no bigger than a pencil eraser! The upper surface of each plant body (or "thalli") is usually pale greenish-white, but sometimes bluish-black. The lower surface is white and cottony. Urn-shaped outgrowths and tiny hair-like structures are two of the species' distinguishing features.

Where does the seaside centipede lichen live?

As its name suggests, the seaside centipede lichen is found where the land meets the sea. Just any old seaside won't do, however. The lichen needs just the right conditions to survive-continuous high humidity, good air circulation, moderate temperatures and shelter from exposure. These habitat requirements are so complex that the species lives only on the lower branches of Sitka spruce trees growing adjacent to the high tide line.

The known distribution of seaside centipede lichen is on the west coast of Vancouver Island. The core of its distribution is in and around Pacific Rim National Park Reserve of Canada. In 2004 the seaside centipede lichen was found 130 kilometres to the northwest of the park in Kyuquot Sound. There are also seaside centipede lichen at one site in Oregon in the United States.

A map of seaside centipede lichen locations in Canada.
Much of the seaside centipede lichen's range in Canada falls within Pacific Rim National Park Reserve.
© Parks Canada