International Journal of Marine Science, 2016, Vol.6, No.16 1
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coenosteum structure, construction of axial and radial
corallites and their interrelations serve as the main
characteristics for identification of genera and species.
The main distinctive feature of
Acropora
from
Anacropora
, as well as from all other scleractinian
formation of two types of radial and axial corallites,
which differ morphologically and functionally. Axial
corallites are beginning to grow from the base of the
colony and grow up with different speeds, diversely
oriented in space according to the genetic abilities of
each species in a particular environment Wednesday.
Constantly increasing at branches in different
directions, they form branching and branchy-plate of
the colony and never form massive colonies. Radial
corallites are forms from the lateral surface of the
axial angles with varying density and have a different
cup. Their growth in aggregate and generates the
diversity of colonies, which is inherent in
Acropora
.
3.1 Form of Colonies
Most
Montipora
species have massive or
massive-encrusting colony shapes. For some species,
colony shape can vary from horizontally lamellar to
digitate-branching and subarborescent even within the
same biotope. In such cases colony shape as a
distinguishing feature can be used together with the
other characteristics, and primary among these are
peculiarities of a corallite form (shape) together with
cenosteume structure.
Coenosteum consists of a basal formation termed
reticulum, as well as a series of combined cenosteume
structures, distributed among corallites and termed
papillae and tuberculae. Papillae protrude in a form of
digitate branchlets on the surface of the reticulum,
having a diameter equal or less than that of a corallite
(Figure 2). Papillae may surround corallites (thecal
papillae), or may be scattered independently of the
corallite (reticular papillae). Both types of papillae can
be simple or compound. Tubercle can be thought of,
as large papillae with sizes can be several times the
diameter of the corallite. Tubercle often merge in rows,
ribs or can be thecal or reticular like papillae, i. e. they
can surround corallites or be dispersed among them.
The main shapes of
Acropora
colonies are termed
arborescent, hispidose, corymbose, caespitose, digitate,
and lamellate (Figure 3).
Figure 3 The appearance of colonies
Acropora
: 1-subarborescent,
2-tree, 3-corymbose, 4-5, subdigitate-cespitose, 6-digitate,
7-lamellar, 8-massively branching
3.2 Structure of Corallites
Corallites of
Montipora
can be immersed or exert
above the cenosteume (Figure 2). They can have or
lack thecal papillae or tuberculae. Immersed corallites
can be deeply embedded in reticulum in such a way
that the latter forms the upper corallite wall, which is
usually funnel-shaped. Such corallites are termed
foveolate. Corals without any additional structures in
reticulum are termed glabrous.
Anacropora
also have the same construction
featuresas
Montipora
, but they form arborescent and
subarborescent colonies with regularly located
corallites on the branch surface. The coenosteum of
these corals has similar construction for all species
and consists of thin tall spinules with complexly
branching top ends, without the formation of tubercle.
Despite good branching,
Anacropora
have no axial
