INVERTEBRATE ZOOLOGY - H. I. Shcherbak - 2008

KINGDOM MULTICELLULAR ANIMALS (METAZOA)

SUBKINGDOM TRUE MULTICELLULAR ANIMALS (EUMETAZOA)

SECTION DIPLOMAXY DIPLOBLASTICA, OR RADIATE ANIMALS (RADIATA)

PHYLUM CNIDARIA, OR COELENTERATES (COELENTERATA)

SUBPHYLUM ANTHOZOA (ANTHOZOA)

CLASS OCTOCORALS (OCTOCORALLIA)

Colonial corals. The polyps feature eight pinnate tentacles and eight septa within the gastral cavity. The internal Skeleton is embedded in the mesoglea and consists of discrete microscopic calcium carbonate needles (sclerites or spicules) formed within specialized Cells known as scleroblasts.

The shape and coloration of the colonies vary considerably. For instance, in Representatives of the order Alcyonacea, where the skeleton consists of separate needles that do not fuse into an Axial Skeleton, the colonies encrust the substrate or appear as spheres or mushrooms (Fig. 93). In species of the order Stolonifera, the skeletal spicules fuse to form tubes connected by transverse plates. The colonies of the well-known organ-pipe coral, Tubipora musica, resemble a pipe organ (Fig. 94). In the order Gorgonacea, the colonies are branched—most commonly tree- or whip-like, flexible, and often delicate and lace-like (Fig. 95). Their skeleton is composed of spicules or horny plates bound together by calcium carbonate or organic horny material.

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Fig. 93. Alcyonaceans (from Naumov et al.): a - mushroom-shaped colony of the soft coral Anthomastus; b - Alcyonium digitatum

Fig. 94. Skeleton of the organ-pipe coral (Tubipora musica) (from Naumov et al.)

Fig. 95. Gorgonians (from Marfenin): a - colony of Corallium rubrum; b - structural diagram:

1 - spicules; 2 - tentacles; 3 — Gonads; 4 - coenosarc canals; 5 - mesoglea; 6 - axial skeleton

These include the red or noble coral (Corallium rubrum), whose horny skeleton is used in jewelry making. Coral necklaces crafted in Mediterranean countries and imported to Ukraine since ancient times are widely known. In species of the order Pennatulacea (sea pens), the colonies are unbranched, quite large, and brightly colored, consisting of a muscular stem formed by the primary polyp, which bears smaller secondary individuals (Fig. 96). Unlike other corals, they do not attach to a substrate; the swollen lower end of the colony freely penetrates the sediment and anchors itself. They are capable of locomotion and can resettle in a new Location. The name of the order derives from the resemblance of certain species' colonies, particularly those of the genus Pennatula, to a bird's feather. Some sea pen species, such as Pennatula phosphorea, can emit a violet, yellowish, or green light at night: in response to strong stimulation, waves of light flashes ripple across the entire colony. In the Black Sea, Virgularia mirabilis can be found, which tolerates significant desalination.

Fig. 96. Sea pens (from Naumov et al.):

a - Pennatula (from Dogiel); b - Veretillum; c - Virgularia; d - Umbellula