Thank you to Stephen B of Scotland aka stephenbuchan@Flickr for sharing today's photograph (original). I've been wanting to feature this species for a while, so much appreciated, Stephen!
If asked to create a list of familiar organisms by the seashore (and lived in a temperate area), I'm betting that most people would not include “lichen” on the list. Narrowing it down to a list of the organisms in the intertidal (the band of life between the high-tide and low-tide marks), and I'm still willing to bet lichen would be absent from most lists. Mussels, yes. Barnacles, yes. Seastars, likely. Seaweed, yes. Lichen? Not likely, unless you know that the black patch of what looks like oil residue is not what it first appears to be.
Sea tar or black seaside lichen is found along coastal rocky shores throughout much of the temperate parts of the world. In these areas, it is often a component of the upper intertidal zone and, above that, the salt-spray zone. To give a rather unscientific example of how it is overlooked, its near-constant intertidal companion with a similar distribution range, Mytilus edulis (or blue mussel / common mussel) receives nearly 600 000 hits on a popular search engine; Verrucaria maura? Fewer than a thousand.
The UK-based Field Studies Council has a small article about tar lichens in general, and a specific page about Verrucaria maura as well. Through photographs, Seaweeds of Alaska reveals how Verrucaria maura can be seen from the air. A closer photograph of the banding caused by lichens is displayed in a story about lichen study in the Gwaii Haanas National Park Reserve of British Columbia: Time for Nature – Learning About Lichens.
How interesting! If I walked by it, I never would have guessed that it was a living organism. Thanks for the enlightenment.
It's extremely interesting! Living on the seaside in Brittany, an area that has seen several major oil spills, I always thought the black marks on rocks were traces of oil spills.
Now... How can I be sure if it is oil or if it is a lichen?
Ah! but Edulis tells why it is more sought after.
I grew up in Newburyport Massachusetts. There is a barrier reaf island, called Plum Island. At one end there are many rocks and many lichen. They are very interesting and I am so pleased to see a photograph of them.
Thank you,
Margaret-Rae
Thanks for the lichen picture. I live in an area where there is lots of it and am curious about it, so the explanation was helpful.