What are Lichens and how do they live?
Lichens are 'dual' organisms, consisting of two or more different forms of life living together symbiotically in a body and all of which benefit from the partnership. Generally the main part of the Lichen is a fungus and the other part being a green alga or cyanobacterium. The function of the alga or cyanobacterium is to produce nutrients via the process of photosynthesis that then are used to feed both parts. The fungus has the basic function of creating a body which forms a sheltered environment protecting against the elements. The fungus also produces chemical compounds that build up to create a protective 'sunscreen' layer over the photosynthetic partner.
There are four main Lichen growth forms each having many subcategories.
1. Crustose - these are encrusted forms and they cannot be removed from surfaces without them crumbling away.
2. Squamulose -
3. Foliose - these can be removed very easily using a knife and they are attached with root like threads. They are leaf like and spread across in a hroizontal layer over surfaces.
4. Fructicose - these can be easily removed by hand and they are much more shrub like with many branches.
Reproduction
Most Lichens reproduce by production of spores, however some also reproduce by having parts of the lichen breaking off and simply growing somewhere else. If a lichen has a powdery substance on the outside then these are the bits of lichen that will break off and spread to create new ones. These bits contain both fungal and alga partners and are known as soredia. When the the spores break off they do not have any of the alga cells and although they can germinate once leaving the Lichen they can only create a new lichen if they find a suitable alga partner as the fungus cannot survive on its own so will die.
Growth
Lichens tend to grow very slowly and their growth is greatly affected by the environment around them. For example small encrusting lichens can grow as little as 1mm each year and larger forms can grow up to 1cm per year. The lichens use their large surface area to absorb minerals and water from the atmosphere and this is why they tend to struggle to grow in areas with high pollution with different species being able to stand different levels of pollution. This therefore makes them a good indicator of air pollution.
They can grow nearly anywhere and it is thought that Lichens cover about 8% of land surface. Lichens tend to grow especially well on rocky coasts, mountain summits, icy polar regions and in steamy tropical rain forests.
Uses for Lichens
Lichens have many practical uses, as well as being an indicator of air pollution, they can be used to make a variety of different coloured dyes. They also create a lot of acids which we use, for example litmus dye and some of the species contain substances with antibiotic properties which can be more effective than penicillin.
Lichens. Available at http://countrysideinfo.co.uk/fungi/lichens.html (accessed 4th April 2013)
Stuff on Rocks 2: All about Lichens. Available at http://watchingtheworldwakeup.blogspot.co.uk/2009/03/stuff-on-rocks-2-all-about-lichen.html (accessed 4th April 2013)
What are Lichens? Available at: http://www.britishlichens.co.uk/whatarelichens.html (accessed 4th April 2013)
There are four main Lichen growth forms each having many subcategories.
1. Crustose - these are encrusted forms and they cannot be removed from surfaces without them crumbling away.
2. Squamulose -
3. Foliose - these can be removed very easily using a knife and they are attached with root like threads. They are leaf like and spread across in a hroizontal layer over surfaces.
4. Fructicose - these can be easily removed by hand and they are much more shrub like with many branches.
Reproduction
Most Lichens reproduce by production of spores, however some also reproduce by having parts of the lichen breaking off and simply growing somewhere else. If a lichen has a powdery substance on the outside then these are the bits of lichen that will break off and spread to create new ones. These bits contain both fungal and alga partners and are known as soredia. When the the spores break off they do not have any of the alga cells and although they can germinate once leaving the Lichen they can only create a new lichen if they find a suitable alga partner as the fungus cannot survive on its own so will die.
Growth
Lichens tend to grow very slowly and their growth is greatly affected by the environment around them. For example small encrusting lichens can grow as little as 1mm each year and larger forms can grow up to 1cm per year. The lichens use their large surface area to absorb minerals and water from the atmosphere and this is why they tend to struggle to grow in areas with high pollution with different species being able to stand different levels of pollution. This therefore makes them a good indicator of air pollution.
They can grow nearly anywhere and it is thought that Lichens cover about 8% of land surface. Lichens tend to grow especially well on rocky coasts, mountain summits, icy polar regions and in steamy tropical rain forests.
Uses for Lichens
Lichens have many practical uses, as well as being an indicator of air pollution, they can be used to make a variety of different coloured dyes. They also create a lot of acids which we use, for example litmus dye and some of the species contain substances with antibiotic properties which can be more effective than penicillin.
Biography
Lichens. Available at http://countrysideinfo.co.uk/fungi/lichens.html (accessed 4th April 2013)
Stuff on Rocks 2: All about Lichens. Available at http://watchingtheworldwakeup.blogspot.co.uk/2009/03/stuff-on-rocks-2-all-about-lichen.html (accessed 4th April 2013)
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