• Issue: March 1986
  • Designer: A. Glaser
  • Stamp size: 40 x 25.7 mm
  • Plate no.: 2 - 4
  • Sheet of 15 stamps Tabs: 5
  • Printers: E. Lewin-Epstein Ltd.
  • Method of printing: Photolithography

Corals are perhaps the most appropriate organisms to symbolize the exotic nature of the Red Sea underwater seascapes. These exclusively marine animals that thrive in all warm seas stand apart from other marine animal groups, due to several properties. The most important of these properties is that they are the dominant constituent of the most luxuriant underwater phenomenon - the coral reef.

People inhabiting the tropical shores normally identify the term "coral" with the bleached stony heads, often assuming the shape of a petrified tree, which are collected and sold as souvenirs. Few are aware of the fact that these are only the skeletons of tiny and vividly-coloured flower-like coral animals, related to sea anemones, that live in huge aggregations, or colonies. A coral colony is usually initiated by the settlement on a rocky surface of a free-swimming coral larva, called a planula. Subsequently it metamorphoses and produces a polyp that grows and later reproduces asexually, by splitting into two or more daughter-polyps. The polyp may alternatively produce smaller polyps by budding. The earlier polyps ultimately die, and are buried beneath their offspring. The number of polyps thus produced increases gradually reaching, in "older" colonies, many millions. Although such colonies attain a size of several metres, they form a continuous organic cover over an inert massive skeleton.

The polyp is basically a predator, preying actively upon the tiny swimming organisms, known collectively as the plankton. Its mouth is situated in the uppermost part of the body, fringed by one or several rings of tentacles, which are equipped with highly specialized microscopic stinging cells, used in the paralyzing and catching of their prey.

The coral polyps maintain their ability to reproduce sexually. Their sex organs, known as gonads, develop inside the body cavity. At the onset of reproduction the sperm cells swim to reach the egg cells in the female polyps. However, many corals are bi-sexual (hermaphro-ditic), producing both eggs and sperm cells. Some even exercise self-fertilization. After the gametes fuse a larval embryo is freed, swimming for several hours before settling on the hard-bottom and starting a new colony by asexual reproduction. In many coral species reproduction or larval expulsion is perfectly timed, often responding to the lunar periodicity.

The corals are grouped into several taxonomical orders, differing in their polyp or colony form, mode of asexual reproduction, skeletal structure, and exquisite colour variation.

More than two hundred coral species have hitherto been recorded from the northern Red Sea. The three genera, illustrated in the present stamps, exemplify the extreme diversity shown by Red Sea corals:

Goniopora has a well-developed chalky skeleton. It is deposited by the ectoderm tissue, forming a cup-like polyp basis, with 6, 12 or 18 radial walls. The number of tentacles is also a multiple of six, hence their collective scientific name Hexacorallia. Most hexacorals engage in a symbiotic relationship with microscopic unicellular algae. called zooxanthellae, that fill the coral's surface cells and are responsible for the latter's green-yellowish colours. The symbiotic plants use the coral's waste products to build their tissues by photosynthesis, and in return supply part of the host's oxygen and food requirements. They also play an important role in the deposition of the chalky skeleton. The metabolism of most hard-skeleton corals depends on these algae to such an extent that they thrive only in sunlit shallow water habitats where the algae can photosynthesize. In the shallow tropical environments they form, together with other calcium carbonate depositing organisms, massive coral reefs.

At least four species of Goniopora live in the Red Sea, differing in polyp size, number of tentacles, etc.

Balanophyllia, another hexacoral, lives in shady habitats - underneath ledges and inside underwater caves. Its long tentacles are almost transparent, and have many stinging cells. This coral, which does not possess symbiotic algae, has yellow-orange pigment particles in its skin. The colony seldom exceeds ten polyps, and the skeleton is fragile. Hence, it is not considered a reef-building coral. There is only one species, Balanophyllia coccinea.

Dendronephthya represents another coral group - the soft corals. These corals are characterized by an inner skeleton composed of chalky spicules embedded in soft tissue. The coral polyp has eight tentacles and eight inner septa, hence their collective name octocorallia.

The structure of octocorals often resembles that of land plants - long, branched stems, adorned by minute flower-like polyps. Like plants, the soft-corals are stabilized by an inner water turgidity. Through the semi-transparent reddish skin of Dendronephthya a mosaic of tiny white or purple spicules can be seen. Upon a soft coral's death its tissues disintegrate and the spicules are widely scattered. Therefore, the contribution of soft corals to the reef framework is negligible.

Many species of Dendronephthya are found in the Red Sea, several of which were first described here.

It is difficult to over-estimate the role of corals in forming and maintaining the ecosystem which, like an underwater "forest," constitutes a habitat in which a multitude of crabs, snails and fish find shelter and nourishment. In spite of the relatively small area occupied by coral reefs, Eilat shores have gained a worldwide reputation for colourfulness and diversity of their reefs. Destruction of coral colonies, whose growth rate is very slow, puts an end to this unique habitat and its inhabitants.

It is therefore hardly surprising that the preservation of Filat coral reefs has become the focus of nature conservation efforts in Israel. Old timers still remember the huge destruction of corals during the fifties, when curious visitors and greedy inhabitants broke and collected many live coral colonies, thus denuding entire reef areas of coral and fish alike. Only a consistent educational campaign carried out by the Society for the Protection of Nature in Israel and the Nature Reserve Authority brought an end to these illegal activities. Furthermore, Filat corals turned into an important tourist attraction, from which many of the townsfolk profit, directly and indirectly. Nevertheless, Filat coral reefs still face many dangers. Pollution by oil, phosphates and urban waste threaten to rupture the delicately balanced reef. Careless visitors who tread over the reef, crush the fragile stony corals and harm the shallow coral colonies.

Let us cherish these gems of nature for our own sake and for the benefit of the generations to come.

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Red Sea corals