- algae
A diverse group of mostly aquatic organisms that can photosynthesise and produce carbohydrates, ranging from single-celled species to large seaweeds.
Green algae inside lichens provide carbohydrates that sustain their fungal partners.
- autotroph
An organism that produces its own energy-rich compounds using light or chemical reactions rather than consuming other organisms.
Green plants and algae are autotrophs, creating carbohydrates from carbon dioxide and water through photosynthesis.
- colony
A group of organisms of the same species living together in close association, often cooperating or sharing resources within a defined area.
A patch of lichens on the bark of a tree can be considered a colony, as the fungal and algal partners grow together in one place.
- cyanobacteria
A group of bacteria capable of photosynthesis, often forming colonies, and sometimes partnering with fungi to create lichens.
Some lichens contain cyanobacteria instead of algae, allowing them to fix nitrogen as well as photosynthesise.
- heterotroph
An organism that obtains energy and nutrients by consuming other organisms or organic matter.
Fungi are heterotrophs, relying on other organisms for the organic compounds they need.
- mutualism
A type of ecological interaction in which two species both benefit from their association.
In lichens, fungi gain carbohydrates from photosynthetic algae or cyanobacteria, while the algae receive water and shelter from the fungi.
- nitrophilous
Describes organisms that thrive in environments with high levels of nitrogen compounds.
Certain urban lichens are nitrophilous and grow well on tree bark enriched with nitrogen from air pollution or construction dust.
- substrate
The surface or material on which an organism lives, grows, or obtains nourishment.
Tree bark, bare rock, and soil can all serve as substrates for lichens.