Description
Coral is a collective name for marine animals in the Anthozoa class. These are tiny creatures, only a few millimeters long, that, with their tentacles, resemble a sea anemone (see also Coelenterates). These creatures, also called polyps, often live in colonies. The brain coral in the photo is an example of such a colony. Coral colonies are often part of coral reefs. Within the Anthozoa class, we distinguish two subclasses: Alcyonaria and Zoantharia. Alcyonaria are also called Octocorallia, after the eight (octo) tentacles each polyp has. The corals in this group include soft corals: they do not produce an external calcareous skeleton. Zoantharia, or Hexacorallia, are polyps with six (hexa) tentacles or a multiple thereof. The corals that build coral reefs, limestone formations, belong to this group. Reef-building corals are colonial corals. The polyps from the colony collectively create an external calcareous skeleton. This occurs on top of the skeleton of deceased polyps from the same colony. This is how coral reefs grow slowly but surely. There are also solitary corals: they grow individually and within their own external calcareous skeleton. Currently, about 4500 species of coral are known.[1] Locally, they form large colonies—banks and reefs, for example, the 2300 km long Great Barrier Reef off the coast of Australia. Corals grow in all warm and clean seas and oceans. In historical times, they were common in the Mediterranean Sea near Tunisia, Algeria, Italy, and the islands of Corsica, Sardinia, and Sicily. The red and orange-red forms still occur here, but to a lesser extent. Coral also grows in the Bay of Biscay. White corals are known from the Sea of Japan, salmon-red off the coast of Taiwan, pink corals grow near Midway Island in the Pacific Ocean, and black corals grow near the Hawaiian Islands. Corals from the Red Sea and the Indian Ocean are famous, occurring near the islands of Socotra and Mauritius, among other places. Black corals, called kabars, can reach up to 3 meters in length and have a diameter of 25 cm. This species also lives in the South China Sea and off the coast of Cuba. Blue corals, called akosi, were discovered off the coast of Cameroon, possibly the rarest coral species. Blue corals are also...
Coral
Described on the Funafuti atoll in the Pacific Ocean. Recently, yellow-brown corals have been found in the northern Atlantic Ocean near the Aleutian Islands and Alaska. Speckled corals occur at depths of 200 meters, and the silvery-pearlescent angel corals hold a special place. Red coral, Corrallium rubrum, is the most sought-after coral. Numerous trade names exist, depending on the location and quality. The color is uniformly light red to salmon-colored Momo, medium-red Sardegna, and oxblood-red Moro, soft pink with whitish or soft pink spots angel skin coral. Black coral consists of organic, keratinous material. Like blue coral, it is commercially insignificant. The Great Barrier Reef, northeast of Australia, consists of two thousand kilometers of coral reefs, a structure unparalleled anywhere else in the world. The reefs are built by millions of coral polyps that can produce calcium thanks in part to the single-celled algae living in their tissues. Reef-building shallow-water coral polyps (e.g., brain coral – Colpophyllia sp.) are found in clear saltwater with a minimum temperature of 20°C. They are absent on the eastern coast of the major oceans due to the prevailing cold currents and where silt-rich water is brought in by rivers. Three reef types can be distinguished: the coastal reef, the barrier reef, and the atoll (see also coral reef). Reef-building cold-water corals (Lophelia pertusa) are found from 200 m to 2000 m deep. Corals reproduce both sexually and asexually. Due to stress and disturbance of the habitat, sexual reproduction often ceases, while this is crucial for the genetic diversity of coral and therefore for the conservation of coral reefs. Rotterdam Zoo is involved in various research programs to ensure better sexual reproduction, both in aquariums and in the wild. Coral is named after the Latin word coralliu and the Greek word korallion, respectively.
