The field of marine biology has been abuzz recently due to an exciting discovery at the very depths of the sea. Researchers have unearthed five new species of Black Corals, dwelling nearly 2,500 feet (762 metres) below the surface within the confines of the Great Barrier Reef and Coral Sea off the coast of Australia.
Understanding Black Corals
Black corals, scientifically known as Anthozoa: Antipatharia, are a fascinating anomaly in the aquatic world. They inhabit both shallow waters as well as the depths of over 26,000 feet (8,000 metres) and can live for more than 4,000 years. However, the taxonomy of black corals is not as well understood as many other anthozoan groups.
These corals present a wide array of shapes and forms, ranging from feathery branches and fan-like structures to straight whip-like formations. Unlike their vibrant relatives in shallower waters that derive their energy from the sun through photosynthesis, black corals are filter feeders subsisting on tiny zooplankton prevalent in deep waters.
Black corals play a vital role in ocean ecosystems, acting as significant habitats where fish and invertebrates find food and protection from predators in what would otherwise be a plain, desolate seabed. For instance, a single black coral colony collected off the Californian coast in 2005 was home to an astounding 2,554 individual invertebrates.
Coral Reefs: An Overview
Corals are spineless marine invertebrates that fall under the phylum Cnidaria and the class Anthozoa in scientific classification. A coral structure consists of identical polyps, which house microscopic algae called zooxanthellae within their tissues. This mutually beneficial relationship enables the corals to get the necessary compounds for photosynthesis, while the zooxanthellae receive organic products of photosynthesis from the corals to make calcium carbonate skeletons.
Giving life to the “rainforests of the seas”, corals display unique and beautiful colors thanks to the zooxanthellae. The coral community is further divided into two kinds: hard corals that extract calcium carbonate from seawater to make rigid skeletons, forming the primary reef-building corals, and soft corals which do not produce such a skeleton but are present within a reef ecosystem.
Significance of Coral Reefs
Though occupying only 1% of the seafloor, coral reefs support over 25% of marine biodiversity. The diverse marine life supported by reefs contributes significantly to global fishing industries. Furthermore, coral reef systems generate an annual economic value of USD 2.7 trillion through goods, service trade, and tourism.
Examining Past Examination Questions
Various questions on corals and their symbiotic relationships have appeared in previous year examinations. In the 2021 UPSC Civil Services Preliminary Examination, one of the questions was about which species can establish a symbiotic relationship with other organisms. Cnidarians, Fungi, and Protozoa were listed as options, and the correct answer included all three because they can form symbiotic relationships, whether mutualistic or otherwise.
Another question that appeared in the 2018 exam highlighted the diversity and distribution of the world’s coral reefs. The statements given included that most of the world’s coral reefs are in tropical waters, more than one-third of these coral reefs are located in Australia, Indonesia, and the Philippines, and coral reefs host more animal phyla than tropical rainforests. All these statements were found to be accurate.
In the 2014 exam, the question was about identifying which of the given locations have coral reefs. The options were Andaman and Nicobar Islands, Gulf of Kachchh, Gulf of Mannar, and Sunderbans. The correct answer was the first three options.
The 2019 Mains examination included a question on assessing the impact of global warming on coral reefs with examples, reflecting the relevance and significance of coral reef ecosystems in the context of environmental changes.