With its cylindrical-shaped, thick, fleshy polyp and radiating tentacles, the distinctive Cynarina lacrymalis is a highly conspicuous coral within the reef environment (3)(4). Thick septa project inwards from the polyp wall, and are surrounded by large, rounded or lobed teeth-like projections (3). During the day, the translucent wall surrounding the sac-like body cavity may inflate with water, swelling to twice its normal size during periods of low light, greatly increasing the surface area of the body and the photosynthesisingzooxanthellae exposed to the sunlight (3)(4). Cynarina lacrymalis is a solitary coral that is most often attached to the sea bed, although it may also be free-living(4). It is typically a mixture of green or brown in colour, but may also be pink, and sometimes other colours. This unique coral is the sole member of the Cynarinagenus(3).
Like many coral species, Cynarina lacrymalis is zooxanthellate, which means that its tissues contain large numbers of single-celled algae called zooxanthellae. The coral and the algae have a symbiotic relationship in which the algae gain a safe, stable environment within the coral's tissues, while the coral receives nutrients produced by the algae through photosynthesis. By harnessing the sun's energy in this way, corals are able to grow rapidly and form vast reef structures, but are constrained to live near the water surface. While, on average, zooxanthellate coral can obtain around 70 percent of its nutrient requirements from zooxanthellaephotosynthesis, the coral may also feed on zooplankton(3).
With an estimated 20 percent of the world’s coral reefs already destroyed, Cynarina lacrymalis faces many threats that are affecting coral reefs globally (5)(6). Worldwide there is increasing pressure on coastal resources resulting from human population growth and technological development. Consequently, there has been a significant increase in domestic and agricultural waste in the oceans, poor land-use practices that result in an increase in sediment running on to the reefs, and over-fishing, which can have ‘knock-on’ effects on the reef (5). However, the major threat to corals is global climate change, with the expected rise in ocean temperatures increasing the risk of coral ‘bleaching’, in which the stressed coral expels its zooxanthellae, often resulting in the death of the coral. Climate change may also lead to more frequent, severe storms, which can damage reefs, and rising carbon dioxide levels may make the ocean increasingly acidic. Such stresses can also make corals more susceptible to disease, parasites and predators, such as the crown-of-thorns sea star (Acanthaster planci) (5)(6)(7).
In addition to being listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which makes it an offence to trade this species without a permit, Cynarina lacrymalis also forms part of the reef community in numerous marine protected areas. To specifically conserve this coral, recommendations have been made for a raft of studies into various aspects of its biology, population status, habitat and threats to its survival (1).
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Simple plants that lack roots, stems and leaves but contain the green pigment chlorophyll. Most occur in marine and freshwater habitats.
Relating to corals: corals that are not attached to the substrate.
A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
Metabolic process characteristic in which carbon dioxide is broken down, using energy from sunlight. Organic compounds are made and oxygen is given off as a by-product.
Typically sedentary soft-bodied component of cnidaria, a group of simple aquatic animals including the sea anemones, corals and jellyfish. A polyp comprises a trunk that is fixed at the base, and a mouth that is placed at the opposite end of the trunk and is surrounded by tentacles.
In a coral, radial elements that project inwards from the corallite wall (the skeletal wall of an individual coral polyp).
Relationship in which two organisms form a close association. The term is now usually used only for associations that benefit both organisms (a mutualism).
Tiny aquatic animals that drift with currents or swim weakly in water.
Single-celled dinoflagellates that form symbiotic relationships with hermatypic ‘reef-building’ corals.
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