The World of Coral Reefs
29
Organisms of the coral reef
In
order to better understand the ecology of the coral
reef environment it is iinportant to have an overview of
the main species groups which occur there. This final
section of the present chapter provides a background to
some of the main groups of organisms on coral reefs,
focussing on the larger or more conspicuous life forms. A
number of major groups are taken in turn, each being
briefly described, with their role in the reef ecosystem
receiving particular attention. Although the major headings refer to broad taxonomic groupings (such as phyla),
a strict taxonomic hierarchy has not been followed.
Particular groups have rather been selected based on their
importance in the reef environment. For more detailed
taxonomic information readers are referred to the sources
at the end of this chapter
Algae and higher plants
As with other ecosystems, sunlight provides the primary
energy source for life on the coral reef, and photosynthetic organisms capture this light and convert it to the
organic molecules which are the building blocks of life.
Higher plants (the more complex life forms, which dominate on land) have an insignificant role to play in most
reefs. In contrast, algae are present throughout the reef
and are critical, not only as the basis of the complex
trophic pathways, but also as a structural component in
the building of the reefs themselves. Despite this, algae
are not highly conspicuous on the reef, either when compared to terrestrial ecosystems, or even to the marine ecosystems of temperate waters. Four main groups of algae
are recognized.
Blue-green algae (Cyanophyta or cyanobacteria)
These are the simplest forms, being prokaryotic (with a
simple cell structure and lacking a central nucleus) and
related to bacteria. They can be unicellular or filamentous
(with cells arranged in long chains) and are widespread
throughout the reef, although their role and importance
remain little known.
Red algae (Rhodophyta)
These include a great variety of forms and species,
ranging from unicellular to filamentous to complex forms.
A number of species secrete calcareous skeletons and are
referred to as coralline algae. The encrusting coralline
algae, such as Porolithon, are among the most important
plants on the reef, playing a critical role in binding
A shallow scene with branching Acropora corals and various damselfish, Seychelles.
29
Organisms of the coral reef
In
order to better understand the ecology of the coral
reef environment it is iinportant to have an overview of
the main species groups which occur there. This final
section of the present chapter provides a background to
some of the main groups of organisms on coral reefs,
focussing on the larger or more conspicuous life forms. A
number of major groups are taken in turn, each being
briefly described, with their role in the reef ecosystem
receiving particular attention. Although the major headings refer to broad taxonomic groupings (such as phyla),
a strict taxonomic hierarchy has not been followed.
Particular groups have rather been selected based on their
importance in the reef environment. For more detailed
taxonomic information readers are referred to the sources
at the end of this chapter
Algae and higher plants
As with other ecosystems, sunlight provides the primary
energy source for life on the coral reef, and photosynthetic organisms capture this light and convert it to the
organic molecules which are the building blocks of life.
Higher plants (the more complex life forms, which dominate on land) have an insignificant role to play in most
reefs. In contrast, algae are present throughout the reef
and are critical, not only as the basis of the complex
trophic pathways, but also as a structural component in
the building of the reefs themselves. Despite this, algae
are not highly conspicuous on the reef, either when compared to terrestrial ecosystems, or even to the marine ecosystems of temperate waters. Four main groups of algae
are recognized.
Blue-green algae (Cyanophyta or cyanobacteria)
These are the simplest forms, being prokaryotic (with a
simple cell structure and lacking a central nucleus) and
related to bacteria. They can be unicellular or filamentous
(with cells arranged in long chains) and are widespread
throughout the reef, although their role and importance
remain little known.
Red algae (Rhodophyta)
These include a great variety of forms and species,
ranging from unicellular to filamentous to complex forms.
A number of species secrete calcareous skeletons and are
referred to as coralline algae. The encrusting coralline
algae, such as Porolithon, are among the most important
plants on the reef, playing a critical role in binding
A shallow scene with branching Acropora corals and various damselfish, Seychelles.