About 75 Percent of Marine Animals Glow

Hawaii’s marine life comes in a rainbow of colors, from the black and yellow hues of our butterflyfish to the red and blue tints of our parrotfish. These vibrant creatures keep guests coming for our Maui snorkel tours time and time again. Their flashy colors wouldn’t exist without the sunlight, and all its various wavelengths bouncing around and reflecting back at us. But what happens in the dark? Light can only penetrate to 656 feet into the ocean. Now, consider that the average depth of the ocean is about 14,000 feet. You can just imagine how much of the ocean’s residents live in complete darkness. Well, almost complete darkness. As it turns out, glowing marine life is more common than scientists originally thought.

Based on some recent discoveries, scientists have found that an incredible three-quarters of marine animals create their own light, which is known as bioluminescence. On April 4, 2017, a study published in the journal Scientific Reports helped to quantify how many species are capable of producing light.

It turns out that the majority of sea life can glow, including jellyfish, squids, worms, and many others, not just the popularized angler fish that lures prey with their little flashing lights. Scientists are also starting to look more carefully at which species are bright versus dim. Most are subtle with their glow, which made their abilities easy to miss, especially given the limitations of many camera types. Also, when you’re in an environment with no outside light source, a little of your own goes a long way. Most of these creatures are careful with their light levels, because they don’t want to attract predators by being too flashy. In fact, many can turn their lights off when they’re feeling cautious.

One of the most fascinating aspects of these recent discoveries is that the researchers found that bioluminescence included approximately 75 percent of creatures across all layers of the ocean, not just the deeper waters. This was just as surprising to scientists as everyone else, because it was commonly assumed that deep dwellers were more likely to glow. Since their research has only been performed in Monterey Bay, off the coast of California, there’s always a chance that the percentages will shift as more locations are studied around the world. That being said, if depth isn’t a factor, we may soon find out that the vibrant Hawaiian marine life that flourishes in our coral reefs is a little more brilliant than we thought.

The study found that the largest of these¬†bioluminescent creatures were the jellyfish and siphonophores (like the Portuguese man ‘o war). In fact, 99 percent of the species in those groups were found to produce light. As if people didn’t find jellyfish mesmerizing enough! The biggest share of the glow found specifically between 4,920 feet and 7,380 feet actually came from marine worms. Below 7,380 feet, around half the bioluminescent organisms were larvaceans, free-swimming little filter feeders.

Another exciting part of the study to consider is that bioluminescence may be able to help marine scientists estimate the number of animals in the deep ocean. Once they find out the proportion of animals that glow, they could possibly measure the brightness of the surrounding bioluminescence to estimate the total number of individuals in the area.

If you happen to be a fellow marine life enthusiast and you want to learn more, you can read about the study published in Scientific Reports. In the meantime, we hope to see you aboard one of our Hawaii snorkeling tours.

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