these blown glass ‘bubbles’
represent progressions of biological evolution in small worlds. the liquids
inside the spheres are cultures of cyanobacteria, a different type in
each ecosystem (each type being a different colour). these suspensions
of microscopic phytoplankton are growing in a nutrient broth that is made
up to a specific recipe, containing all the chemicals required for their
the cyanobacteria are “simple”, single-celled, photosynthetic
organisms, considered to be relatively closely related to the organisms
that caused our atmosphere to have oxygen in it, about 3.5 billion years
ago. their colour depends on the main photosynthetic pigment that they
use to capture light photons.
photosynthesis is the process by which organisms convert light energy
into chemical energy, this chemical energy is then stored in carbon-containing
molecules (sugars and other carbohydrates) which are built up from carbon
dioxide molecules (the carbon is referred to as being ‘fixed’
by this means).
the process of photosynthesis underpins most of the extant life on earth,
both serving to provide a food source for non-photosynthetic organisms
(e.g. animals), and to keep the atmosphere oxygenated, giving us air to
breathe. all photosynthetic organisms use the green pigment chlorophyll
a, but many aquatic photosynthetic organisms also use red and orange pigments.
in aquatic environments this is as a result of the attenuation of light
in the water column, blue light (which is absorbed by red pigments) travelling
the furthest in most waterbodies. the reddish pigments tend to be seen
in the “primitive” organisms (e.g. cyanobacteria), and so
in ‘Small world’ the changing colours along the work reflect
the process of evolution (e.g. from oceanic bacteria to terrestrial ‘higher’
plants; from the past to contemporary worlds).
organisms that conduct photosynthesis stand at the gateway to the living
world, at the interface where the inorganic becomes organic, where non-life