Coral – Plant? Animal? Mineral?

In honor of the recent buzz about coral reefs with Netlix’s newest documentary, Chasing Coral and various awareness weeks going around social media, I thought it would be the perfect topic for my first post! I really love corals, and I know I am not alone. Corals are some of the most popular marine organisms on the planet. And why not? They are stunningly beautiful, complex, full of color and life, and are found in equally beautiful tropical locations. They are a perfect poster child for our oceans. They are also fascinating for a variety of reasons. Despite being around for millions of years, scientists are still learning new things about them all the time. Instead of rehashing the same basic information, I would like to share some lesser known info and some cool newer discoveries! Let’s examine a common misconception…

Bleaching does NOT automatically equal dead.

It’s certainly not a good thing, and can potentially lead to mortality, but in and of itself, bleached corals are not dead. You might have learned before that corals have a symbiotic relationship with single-celled algae (as a group called zooxanthellae in case you were wondering). The coral provides the algae a habitat, and the algae produces an abundance of sugars through photosynthesis, and the corals get to ‘eat’ the extras. In order to maintain a healthy relationship, the surrounding environmental factors have to be just right, like in Goldilocks and the Three Bears. If the water becomes too hot/cold, acidic, cloudy, etc., then the algae will leave (or be expelled from) the coral. This is known as bleaching (as the algae provides coral with much of its visible color, when it leaves, the coral’s white skeleton is visible). The coral does not immediately die when the algae leaves however. It can still catch food floating by and survive for a while (hmm I sense a follow up post here…). If conditions do not improve or instead worsen, then the corals could die. But if the conditions improve, the algae can come back and the relationship will continue. So when you see disturbing reports of reefs with large bleaching events, it is not quite as bad as you may think. It is certainly not a good thing, and the increase in bleaching events is definitely very alarming (another coming post!). But, strictly speaking, bleaching does not automatically equal death.