5 Things you Didn’t Know about Coral Reefs

Updated: Nov 2, 2020


Corals reefs are known as the rainforests of the ocean. And rightly so, they cover less than 1% of the ocean floor yet are home to almost 25% of all marine species in the world. They also support millions of people who rely on them for food, jobs and protection from natural disasters. Here are some weird and wonderful facts about coral reefs. Enjoy!


1. You would have almost definitely heard of coral bleaching (unless you’ve been living under a rock) because it’s something scientists all around the world are panicking about right now. You can tell when corals have bleached when their colour is bone white. This lack of colour is caused by the expulsion of a group of alga called zooxanthellae. Algae is expelled for a bunch of reasons including an increase in temperature and acidic conditions. If the algae experience such conditions, this will essentially cause the coral an extreme amount of stress, so the coral has no choice but to kick the algae out. So, most people think that once the coral expels the algae that the coral polyps just die, but this isn't the case! Corals are animals that can find food on their own, so can survive for a little while without their algae friends. If conditions improve, there is hope for the coral. New algae will be able to colonise, and the coral will revert back to the beautiful colourful creatures that support life on the reef!



2. Corals although animals are stationary for almost their entire lives. Once they have settled as juveniles, they will stay in this one spot for the rest of their lives. This has meant corals evolved many different chemical defences to prevent attacks from predators. These chemicals are what make corals so important to humans and the development of new medicines that could potentially cure untreatable diseases or improve the efficiency of existing ones. Corals have been critical to the advancement of treatments for things like cancer, arthritis, bacterial infections and heart disease (to name a few!). Several studies show that both hard and soft corals have demonstrated anti-inflammatory properties, anti-cancer properties, bone repair AND neurological benefits! Pretty insane for an animal that some people mistake for rocks!


3. Plastic isn't just bad for the megafauna in our oceans, it’s also detrimental to the health and survival of corals. According to several studies, all the pieces of plastic-like bags that get snagged and tangled around corals, are causing infection rates among many different species to soar. Scientists found that 89% of reefs contaminated with plastic are afflicted with disease. Compare that to the 4% found on plastic-free reefs and its pretty alarming. No doubt this huge rise in infection will lead to increased mortality.



4. Coral reproduction is also super interesting and a little bit strange. It varies from species to species. The first mode of reproduction involves clones of the coral polyps budding off the parent polyps and floating away, along with the current and settling where conditions are optimal. Some species will have two separate sexes that will sexually reproduce. However, the most common form of reproduction and arguably the most beautiful involves coral species that are simultaneously male and female (hermaphrodites). These release thousands of small gametes into the water column, usually on or around a full moon. They look like tiny little beads floating in the water. This is truly a sight to behold! I haven't yet been lucky enough to see it with my own eyes, but it is on the bucket list!


5. You may think that coral reefs are only associated with warm tropical countries. However, corals can be found in the cold waters of Scotland, Ireland and even the Arctic! The reefs found there are some of the most abundant and beautiful habitats in the world. Unfortunately, these cold-water reefs are at risk to factors like global warming, over-fishing and dredging just like there tropical cousins. We need to remember to protect the idyllic coral reefs of the tropics AND those found closer to home that are all too often forgotten about.


Mimi x



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