7 Communities of Corals in Reef Ecosystems
Most reef corals belong to the class Anthozoa. Only two of their families are
related to another class of coelenterates-Hydrozoa: Milleporidae and
Stylasteridae. The class of Anthozoa includes the two subclasses
Hexacorallia (or Zoantharia) and Octocorallia, which are different in origin
as well as in their morphology and physiology. The function of reef
construction is mostly performed by the reef-building (or hermatypic)
corals, which form massive calcareous (aragonite) skeletons. The group of
hermatypic corals is represented mostly by the order Scleractinia (subclass
of Hexacorallia). Two species in this group belong to the order of
Octocorallia (Tubipora musica and Heliopora coerulea), and several species
to the class Hydrozoa (hydrocorals Millepora sp. and Stylaster roseus) (see
Fig. 7.1). The hermatypic corals harbor the algal symbionts zooxanthellae,
which greatly accelerate the processes of calcification, thus enabling their
host corals to construct massive colonies (cf. Sect. 1.2). The hexacorals from
other orders of the subclass Hexacorallia: Corallimorpharia, Antipatharia,
and Ceriantharia, including some species of the order Zoanthidea as well as
most octocorals of the subclass Octocorallia, being colonizing animals, also
produce hard skeletons or hard elements of their soft skeletons from the
calcareous material, and thus participate in the production of crumb lime
material. According to their functions in reef building (hermatypeahermatype) and, connected with this function, their possession of algal
symbionts (symbiotic-asymbiotic), all corals could be subdivided into the
following groups (guilds) (Kuhlmann 1985; Schuhmacher and Zibrovius
1985):
1. Hermatypes-symbionts. This group includes most reef-building
scleractinian corals, octocorals and hydrocorals (cf. Fig. 7.1).
2. Hermatypes-asymbionts. These slow-growing corals can construct
massive lime skeletons without the aid of zooxanthellae, in which they
are able to live in dark environments-in caves, tunnels, and deep parts of
the continental slope. Among them are the asymbiotic scleractinians
Tubastrea and Dendrophyllia, and the hydrocoral Sty laster rosacea.
3. Ahermatypes-symbionts. Among scleractinians there could be included
into this group the small fungiids, like Heteropsammia and Diaseris, and
also the coral Leptoseris (fam. Agaricidae), which exist as small single
Most reef corals belong to the class Anthozoa. Only two of their families are
related to another class of coelenterates-Hydrozoa: Milleporidae and
Stylasteridae. The class of Anthozoa includes the two subclasses
Hexacorallia (or Zoantharia) and Octocorallia, which are different in origin
as well as in their morphology and physiology. The function of reef
construction is mostly performed by the reef-building (or hermatypic)
corals, which form massive calcareous (aragonite) skeletons. The group of
hermatypic corals is represented mostly by the order Scleractinia (subclass
of Hexacorallia). Two species in this group belong to the order of
Octocorallia (Tubipora musica and Heliopora coerulea), and several species
to the class Hydrozoa (hydrocorals Millepora sp. and Stylaster roseus) (see
Fig. 7.1). The hermatypic corals harbor the algal symbionts zooxanthellae,
which greatly accelerate the processes of calcification, thus enabling their
host corals to construct massive colonies (cf. Sect. 1.2). The hexacorals from
other orders of the subclass Hexacorallia: Corallimorpharia, Antipatharia,
and Ceriantharia, including some species of the order Zoanthidea as well as
most octocorals of the subclass Octocorallia, being colonizing animals, also
produce hard skeletons or hard elements of their soft skeletons from the
calcareous material, and thus participate in the production of crumb lime
material. According to their functions in reef building (hermatypeahermatype) and, connected with this function, their possession of algal
symbionts (symbiotic-asymbiotic), all corals could be subdivided into the
following groups (guilds) (Kuhlmann 1985; Schuhmacher and Zibrovius
1985):
1. Hermatypes-symbionts. This group includes most reef-building
scleractinian corals, octocorals and hydrocorals (cf. Fig. 7.1).
2. Hermatypes-asymbionts. These slow-growing corals can construct
massive lime skeletons without the aid of zooxanthellae, in which they
are able to live in dark environments-in caves, tunnels, and deep parts of
the continental slope. Among them are the asymbiotic scleractinians
Tubastrea and Dendrophyllia, and the hydrocoral Sty laster rosacea.
3. Ahermatypes-symbionts. Among scleractinians there could be included
into this group the small fungiids, like Heteropsammia and Diaseris, and
also the coral Leptoseris (fam. Agaricidae), which exist as small single