Glossary: Coral reef

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This glossary supports teachers and students with some of the technical language used in the Coral Oceans resources.

Adaptation: the changes in an organism to become more suited to its environment. These can be changes in structure, behaviour, or how the organism functions.

Algae: plant-like life that lack the structures that plants have, such as leaves and roots. Algae includes small, single-celled examples known as micro-algae, and larger, often multi-celled examples such as seaweed, known as macro-algae.

Bleaching: results from the breakdown of the relationship between the coral polyp and the zooxanthellae that lives in its tissue. This is commonly caused by increased sea temperatures. The process is known as bleaching because the zooxanthellae give the coral its colour and so the coral appears white when the zooxanthellae have been ejected. Bleached coral is not dead, but can die if it stays bleached for periods of longer than 4 to 6 weeks.

Buddy system: the practice of diving in pairs for safety reasons, e.g. if there is an equipment failure for one of the divers.

Cnidaria: a phylum of animals, including jellyfish, sea anemones and corals. Cnidarians are found exclusively in aquatic and most marine environments. They get their name from their use of cnidocytes (containing nematocysts) or stinging cells to capture prey.

Consumer: the term given to organisms that get their energy from other organisms rather than through photosynthesis.

Coral: a type of cnidarian that mostly forms large colonies made up of individual polyps, surrounded, in the case of hard corals, by a calcium carbonate structure.

Coral colony: the term used to refer to a collection of coral polyps in a single structure. All the coral polyps within a coral colony are connected and nutrients are shared between them.

Crustacean: a subphylum of arthropods that have hard-jointed shells, including lobsters, crabs, krill, and copepods.

Dive log: a form that divers fill in at the end of their dive. Dive logs are used for safety, to provide a record of underwater exploration and research, and for divers to provide evidence of their experience.

Dive master: a term both for a level of diving proficiency and the individual on an expedition who is in charge of the dive profiles (how deep and how long divers are in the water), as well as the equipment, including refilling air tanks.

Dive signs: a system of signs used by divers to communicate underwater.

Echinoderm: a phylum of marine animals characterised by their radial symmetry and spiny skin. The term echinoderm comes from the Latin for spiny skin. Echinoderms include sea urchins, sea stars (commonly called starfish), and sea cucumbers.

Ecosystem: an ecosystem is a complex set of relationships between animals, plants, and other life and their environment in a given area. An ecosystem can be as small as a section of coral reef, or as large as an entire ocean.

Eutrophication: the process where excess nutrients (often fertiliser from land) increases the amount of algae in the ocean. This results in algal levels that are too great for herbivorous animals to consume. When the excess algae dies, the bacteria feeding on it use increasing amounts of oxygen in their area of the ocean. This reduces the amount of oxygen available to other marine life and can lead to anoxic ‘dead zones’.

Fore reef: the area immediately below the reef crest facing the ocean.

Habitat: the area or environment where a certain animal or other species normally lives. For example, shallow, warm tropical waters are the natural habitat for corals.

Habitat zone: a term used for varied habitats within an ecosystem, defined by environmental factors. Typical coral reef habitat zones include: lagoon, reef crest, fore reef, and reef slope.

Lagoon: the sheltered area between the reef and shore, also known as the reef flat.

Mollusc: a large and varied phylum of animals that contains creatures such as octopus, squid, slugs, snails, and shellfish.

Nematocyst: the sub-cellular stinging mechanism used by jellyfish, coral, and other cnidarians to capture their prey. It has been likened to a microscopic toxic harpoon.

Nutrient: any nourishing substance used by living things for growth, repair and normal functioning. This can include food, as well as minerals such as nitrates and phosphates.

Ocean: the name for the connected body of salt water that covers over 70% of the Earth’s surface. The ocean is divided into five basins: the Arctic Ocean, the Atlantic Ocean, the Indian Ocean, the Pacific Ocean and the Southern Ocean.

Ocean acidification: the process by which atmospheric carbon dioxide is absorbed by the ocean, and through a chemical reaction affects the ocean’s chemistry, lowering the pH.

Photosynthesis: the process used by plants, algae, and some bacteria to make sugars (and thereby energy) from the sun.

Phytoplankton: microscopic plants and algae that drift on the ocean currents.

Plankton: small plants, algae and animals that drift on the ocean currents.

Planula: the name given to coral polyp larva.

Polyp: the animal that makes up the coral reef.

Primary producer: any living thing that receives its energy from the sun.

Primary production: another term for photosynthesis, and which can also refer to chemosynthesis.

Reef: traditionally a term for a navigational hazard, ‘reef’ now more commonly refers to the structures created by coral polyps.

Reef crest: the exposed top of the reef.

Reef mosaic: the patchwork of coral reefs that make up large areas of reef habitat. The best known example is the Great Barrier Reef, which stretches over 2,300km along the eastern coast of Australia.

Reef slope: the area sloping down from the reef towards the open ocean.

Salinity: the measure of the salt content of water. Typically, the ocean has a range of 31g to 38g of salt per litre.

Scuba diving: the use of ‘self-contained underwater breathing apparatus’ to breath underwater.

Sea: a contained area of ocean (e.g. Mediterranean Sea) or area of sea near to land (e.g. North Sea).

Sedimentation: when particles suspended in the ocean fall to the bottom. For example, soil that has washed out to sea which falls to cover the seafloor.

Substrate: the material that forms the seafloor, e.g. sandy substrate, rocky substrate, etc.

Turbidity: the scientific term for the cloudiness of water.

Zooplankton: small animals, larvae, and eggs that drift on the ocean current.

Zooxanthellae: a type of algae that lives inside the tissue of a coral polyp, typically supplying it with 70% to 90% of its energy.

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