358
Nutrition of Corals
experiments catching and swallowing various zooplankters, such as
copepods, amphipods, and chaetognaths (Grigg 1965). The same was true
for the Caribbean black corals Cirripathes lutkeni, Antipathes pennacea and
A. peduta. They catch the food particles with the aid of mucus nets. The
prey thus caught is dragged to the area around the oral disc. From there it is
driven to the mouth by cilia and swallowed. Large preys which the polyp
caught, but cannot swallow, may be digested outside the gastral cavity with
the aid of the polyp's powerful mesenterial filaments (Lewis 1978). As it is
able to use efficiently the mucus nets and the ciliar apparatus the polyp
could be supposed to make use also of bacterioplankton and DOM as
additional sources of heterotrophic nutrition for these corals, as do
scleractinian corals.
The polyps of ceriantharians are morphologicall very similar to those in
Antipatharia. Thus they too could be supposed to have the same spectrum
of feeding. They have active proteases in their mesentery, which enable
them to digest large preys (Tiffon and Boullon 1975).
As regards the nutrition of the octocorals, this extremely important group
of Anthozoa could be characterized by a high variaty of types of feeding in
their taxa. As octocorals are very vulnerable to mechanical damage and to
any kind of transplantation, they are difficult objects to make experiments
with (Lewis 1982). An important general feature of octocorals is an
apparent reduction of most organs and organelles in them that serve the
function of heterotrophic feeding in scleractinian corals and in other
Hexacorallia (Kawaguti 1964a,b; Mariscal and Bigger 1977). The polyps of
Octocorallia have reduced cnidocils and reduced mesenterial filaments. The
cnidocil, which is so well developed in Sceractinia and is represented in
them by a wide selection of various large and small nematocysts, in
octocorals is represented only by tiny rear nematocysts of the same kind,
which seem to be useless for hunting the mesozooplankters. Many
octocorals have only rudimentary nematocysts which, moreover, are difficult
to locate (Pratt 1906; Gohar 1940; Mariscal and Bigger 1977). The ciliar
epithelium covers like a fur the polyps of Scleractinia and form conical
structures, spirocysts, around their large nematocysts, which accomplish a
key function in their feeding. In octocorals the ciliar epithelium is drastically
reduced, remaining only at the oral disk of polyps and on the surface of
their gullets. The conical structures around their rear nematocysts are absent
sutirely. And finally, the edges of tentacles in the polyps of octocorals are
fringed with pinnules, which on the tentacles of scleractinia are absent
(Lewis 1982).
The above specific features of morphology in the nutritional organs of
octocorals nutrition appeared already at an early stage of their evolution
(Schmidt 1972). This lets us suppose that they had their own strategy of
feeding and capturing preys different from that in scleractinians. Many of
them have symbiotic zooxanthellae. These symbiotic (hermatypic)
octocorals are just the dominating ones on the reefs. Among them are the
Nutrition of Corals
experiments catching and swallowing various zooplankters, such as
copepods, amphipods, and chaetognaths (Grigg 1965). The same was true
for the Caribbean black corals Cirripathes lutkeni, Antipathes pennacea and
A. peduta. They catch the food particles with the aid of mucus nets. The
prey thus caught is dragged to the area around the oral disc. From there it is
driven to the mouth by cilia and swallowed. Large preys which the polyp
caught, but cannot swallow, may be digested outside the gastral cavity with
the aid of the polyp's powerful mesenterial filaments (Lewis 1978). As it is
able to use efficiently the mucus nets and the ciliar apparatus the polyp
could be supposed to make use also of bacterioplankton and DOM as
additional sources of heterotrophic nutrition for these corals, as do
scleractinian corals.
The polyps of ceriantharians are morphologicall very similar to those in
Antipatharia. Thus they too could be supposed to have the same spectrum
of feeding. They have active proteases in their mesentery, which enable
them to digest large preys (Tiffon and Boullon 1975).
As regards the nutrition of the octocorals, this extremely important group
of Anthozoa could be characterized by a high variaty of types of feeding in
their taxa. As octocorals are very vulnerable to mechanical damage and to
any kind of transplantation, they are difficult objects to make experiments
with (Lewis 1982). An important general feature of octocorals is an
apparent reduction of most organs and organelles in them that serve the
function of heterotrophic feeding in scleractinian corals and in other
Hexacorallia (Kawaguti 1964a,b; Mariscal and Bigger 1977). The polyps of
Octocorallia have reduced cnidocils and reduced mesenterial filaments. The
cnidocil, which is so well developed in Sceractinia and is represented in
them by a wide selection of various large and small nematocysts, in
octocorals is represented only by tiny rear nematocysts of the same kind,
which seem to be useless for hunting the mesozooplankters. Many
octocorals have only rudimentary nematocysts which, moreover, are difficult
to locate (Pratt 1906; Gohar 1940; Mariscal and Bigger 1977). The ciliar
epithelium covers like a fur the polyps of Scleractinia and form conical
structures, spirocysts, around their large nematocysts, which accomplish a
key function in their feeding. In octocorals the ciliar epithelium is drastically
reduced, remaining only at the oral disk of polyps and on the surface of
their gullets. The conical structures around their rear nematocysts are absent
sutirely. And finally, the edges of tentacles in the polyps of octocorals are
fringed with pinnules, which on the tentacles of scleractinia are absent
(Lewis 1982).
The above specific features of morphology in the nutritional organs of
octocorals nutrition appeared already at an early stage of their evolution
(Schmidt 1972). This lets us suppose that they had their own strategy of
feeding and capturing preys different from that in scleractinians. Many of
them have symbiotic zooxanthellae. These symbiotic (hermatypic)
octocorals are just the dominating ones on the reefs. Among them are the