Red coral, with its striking color and intricate forms, has fascinated humanity for millennia. This unique marine organism has been transformed into cherished jewelry and art objects across diverse cultures, from ancient Mediterranean civilizations to Native American tribes in the Southwest. Its enduring appeal underscores a deeper story about a delicate living creature and its place in the ocean.
What Is Red Coral?
Red coral is not a plant or a mineral, but an animal belonging to the phylum Cnidaria, which also includes jellyfish and sea anemones. Specifically, it is a type of soft coral within the family Coralliidae, distinguished by its hard, intensely colored skeleton. The most recognized species is Corallium rubrum, often referred to as precious coral.
This marine animal lives as a colony of tiny individual polyps, each possessing eight retractable tentacles. While the polyps themselves are typically white, the coral’s distinctive red, pink, or sometimes white color comes from carotenoid pigments embedded within its calcium carbonate skeleton. This skeleton is composed of numerous stick-like calcium carbonate rods, known as sclerites, that fuse together to form a rigid, branched structure. Colonies can grow up to 50 centimeters in height and attach firmly to rocky substrates. Red coral polyps use their tentacles to capture small invertebrates, zooplankton, and organic particles as food from the surrounding water.
Where Red Corals Live
Red corals typically inhabit deep, dimly lit marine environments, often found in caves, crevices, or on vertical walls. They thrive in areas with strong currents that deliver food particles, while also having low rates of sedimentation. This preference for sheltered, low-light conditions distinguishes them from reef-building corals, which require shallow, sunlit waters.
The species Corallium rubrum is primarily found in the Mediterranean Sea, extending from depths of 10 to 300 meters, though shallower habitats have seen depletion due to historical harvesting. Some populations are also reported in the adjacent Atlantic Ocean. Other Corallium species are native to the western Pacific Ocean, concentrated around Japan and Taiwan, typically occurring at much greater depths, ranging from 350 to 1500 meters below sea level.
The Value of Red Coral
Red coral holds importance from both an ecological and a human perspective. Ecologically, its arborescent, three-dimensional structures provide complex habitats on the seafloor. These structures offer shelter and food sources for a diverse array of marine life, including various fish and invertebrate species. Red coral is a component of the Mediterranean “Coralligenous,” a diverse community where it coexists with other species, forming a habitat with some of the highest biodiversity in the Mediterranean Sea.
For humans, red coral has possessed immense cultural and economic value for thousands of years. Its durable and intensely colored skeleton has been highly sought after for jewelry, art, and talismans since antiquity. Historically, it was traded along routes like the silk and spice roads, and in various cultures, it was believed to offer protection or bring good fortune. Today, red coral jewelry remains highly prized, with its value influenced by its color, hardness, scarcity, and portability.
Threats Facing Red Coral Populations
Red coral populations face multiple threats that jeopardize their long-term survival. Overharvesting is a primary concern, driven by the sustained demand for its use in jewelry and decorative items. This intensive exploitation has led to declining stocks and shifts in population structure, with many areas now having smaller, younger colonies.
Climate change presents additional challenges, particularly through ocean warming and acidification. Rising sea temperatures can cause coral stress, potentially leading to disease, while increased carbon dioxide absorption by the ocean makes the water more acidic. This acidification hinders the coral’s ability to build and maintain its calcium carbonate skeleton, slowing growth and weakening its structure. Compounding these issues is the extremely slow growth rate of red coral. This slow growth means populations recover very slowly from disturbances, making them particularly vulnerable to ongoing pressures.