Fungus Provides UV Protection

close up photograph of yellowish green lichen on a tree

Biological Strategy

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Protect From Light

Access to sunlight is crucial to living systems because it’s the primary energy source for life. However, too much sunlight in the form of ultraviolet radiation (UV) can cause damage to living tissues. Therefore, living systems have strategies to filter out some or all UV radiation. For example, some plants that live in areas exposed to long periods of direct sunlight have reflective surfaces (such as white hairs or powder) that reflect UV light.

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Cooperate/Compete Between Different Species

From parasitism to mutualisms, there are endless interactions between organisms in nature. Interactions between species that lead to a negative outcome for one species are known as competition. Cooperation occurs when organisms work together for the benefit of each organism or species. While competition often occurs over resources or mates, the more biologists have begun to look for examples of cooperation in nature, the more they have found. For example, around 90% of plants have a beneficial partnership with fungi. Fungi provide the plant with nutrients such as nitrogen and phosphorus, in exchange for sugars from the plant.

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Lichens

Lichen (“to lick”): Iceland moss, reindeer lichen, rock tripe

Lichen are composed of two organisms: algae (or cyanobacteria) and fungi. In this symbiotic, or beneficial relationship, algae produce simple sugars through photosynthesis which are consumed by fungi, and fungi provide algae with water and shade. Sometimes referred to as “moss”, lichen superficially resemble, but are not true moss. It is estimated that lichen cover 8% of the Earth’s land surface. From the subzero temperatures of the Arctic to sweltering deserts, lichen can be found on flat surfaces; gravestones, city buildings, rocks, trees, soil, and other flat surfaces. While some lichen have a cracked, crusty appearance, others are more foliose, or leaf-like in appearance. Lichen are currently being used as an inexpensive way to assess air quality, as some are sensitive to pollution and metal contamination. In the Arctic, caribou depend on reindeer lichen (Cladonia spp.) as their main source of food during migration.

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The algal element of lichens is protected from UV radiation by a fungal skin.

Image: Auntie P /

One of many forms of lichen.

Image: Van /

Lichen

Image: Torrey Ritter /

Image: Christine Phillips /

This illustration was submitted as part of an entry for the 2011 Student Design Challenge. The illustration shows a passive indoor system for filtering air and protecting employees from excess UV light.

“Others [lichens] develop minuscule branches and grow into dense curling thickets a few inches high. Their outer skin is formed by the compacted threads of the fungi and is sufficiently impermeable to prevent the loss of water from the partnership; beneath are the algal cells, kept moist and protected from harmful ultra-violet radiation by the fungal skin; and below them, in the centre of the structure, there is looser tissue, also provided by the fungus, where food and water is stored.” (Attenborough 1995:216)

Last Updated August 18, 2016

References

Book

The Private Life of Plants

BBC Books | 21/08/1995 | David Attenborough

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