Monday, 25 June 2012

Elephant No. 267: Lichens

While walking through a park today, I came across a rather pretty piece of bark covered in several types of lichen. I picked it up to use at some point in the future, but it was already beginning to change colour from greens to browns by the time I got home, so I thought I'd better use it today.

Lichens are organisms that result from a symbiotic relationship between a fungus and a photosynthetic "partner" that usually consists of either algae or cyanobacteria. Lichens grow in some of the world's most extreme environments, including deserts, rocky coastlines, tundra, and even slag heaps. They also thrive on leaves and bark, and on bare rock.

Parmeliopsis ambigua, a foliose lichen growing on a tree branch, Germany, 2011.
Photo: Norbert Nagel

Although lichens are widespread, and often live for decades or longer, many are sensitive to environmental changes, including pollution, heavy metals and changes in ozone levels. Because of this sensitivity, they are often used as indicator species by scientists.

Lichens can survive low moisture levels for extended periods of time. When rehydrated, their membranes actually reconfigure over a period of several minutes. Because they have a photosynthetic component, lichens change carbon dioxide into carbon sugars, feeding the host fungus and plant from atmospheric rain and dust. The fungus acts as a moisture reservoir, while the photosynthetic component provides energy.

Lichens come in various shapes and forms, including "foliose" (leafy), "crustose" (crust-like), "fruticose" (branch-like), and "squamulose" (scaly). Sometimes the same lichen fungus can develop into two different forms on the same surface.

British Soldier Lichen.

Despite the fact that lichens must compete with plants for sunlight, they are so small and grow so slowly that they can thrive where other plants may not. They are the first photosynthetic organisms to settle in places without soil, often becoming the sole vegetation in an area, or even a substrate on which other plant material eventually grows. They have no roots, and do not need to absorb water continuously as do most plants.

Although not harmfully parasitic to plants, lichens will destroy rock both chemically and physically. This means that carved stone, such as gravestones and statues, must be kept free of lichen to avoid degradation.

Weirdly enough, lichens can even survive in Space. In 2005, two species of lichen were sealed in a capsule and launched into orbit. Once in orbit, the capsules were opened, and the lichens were directly exposed to the vacuum of Space, including cosmic radiation and fluctuating temperatures. Brought back to Earth 15 days later, the lichens were healthy and showed no sign of damage from their time in Space.

In addition to their importance to the environment, lichens have also been adapted by humans for use as food, traditional medicines, perfumes and dyes. Although some lichens are eaten only when food is scarce, others have served as staples—including Iceland moss, which was consumed across northern Europe in porridge, bread, soup and salad. In some Asian cuisines, certain lichens are even seen as delicacies. Although very few lichens are toxic to humans, the majority of poisonous lichens are yellow in colour.

Gathering of the lichen Umbilicaria esculenta as food.
From Hiroshige II's Shokoku meisho hyakkei
("100 famous views of Japan")
, 1860.

In medicine, some lichens appear to function as antibiotics, while others produce a substance similar to cannabis. There is even a suggestion that certain types of lichen may degrade prions—the infectious agents responsible for spongiform encephalopathy, also known as Jakob Creutzfeldt's disease or Mad Cow disease.

For more than 2,000 years, lichens have also been used to produce red and purple dyes. Testing for pH levels actually uses a dye extracted from lichen. Lichens are also used by model-makers to form trees and shrubs, and are particularly common in model railroad settings and other dioramas.

For today's elephant, I had a fairly small piece of bark, measuring about 5 x 6.3 cm (2 x 2.5 inches). It seemed to have several types of lichen on it, however, so there was a lot to play with.

On the other hand, I would have to play on a very delicate scale, so I decided to use a fine blade. The raw piece was also quite beautiful as it was, so I wanted to preserve as much of the texture as I could. I also knew that I would have to remove material very sparingly, because there would be no way to put anything back on once I sliced it off.

I started by spraying the lichen with water, because it seemed to be drying out and changing colour. I then turned it around every which-way to see if I could find an obvious elephant in it. When I thought I saw an elephant, I started teasing bits of lichen away.

This type of material is incredibly fragile, particuarly when damp. The largest mass had a very spongy texture that didn't yield easily to the tip of my knife blade. I had to use the knife almost vertically, essentially poking the surface and pulling off pinprick-sized pieces.

I liked the background textures as a counterpoint to the orange-green "fluffiness" of the main area, so I didn't scrape all the way down to the bark, except beneath the trunk and neck area. For the rest, I mostly just shaped things, deciding that an abstract would look best. To finish, I swirled the knife around to form an eye.

This was a bit fussy, but I didn't mind, as it took only half an hour. I didn't remove a lot of material—in fact, this probably amounted more to grooming the lichen than anything else, because the main shape was more or less already there.

It's quite fragile, and I have no idea how to preserve the colours once it dries out again, but I like the final piece very much. The different textures and colours are lovely on their own, and I'm definitely going to be on the lookout for similarly pretty pieces to try this again.

Elephant Lore of the Day
I've written before about elephants knowing how to drink from a hose, and how to make and use tools, but the video below surprised me.

In addition to drinking from the hose, this Asian elephant has also learned how to hose itself off.

To Support Elephant Welfare
Elephant sanctuaries (this Wikipedia list allows you to click through to information
on a number of sanctuaries around the world)
Wildlife Trust of India

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