There are so many creatures on Earth with spectacular abilities and unique characteristics. Take the aye-aye, for example. A lemur with bat-like ears, owl-like eyes, and rodent-like teeth, the aye-aye is the world’s largest nocturnal primate. At night, it journeys across the forest canopy, tapping on trees, gnawing holes into the bark, and extracting grubs using its long and narrow middle finger. The aye-aye’s bizarre-looking middle finger has a ball and socket joint, which gives it a wide range of motion.
Then there’s the magnificent frigatebird . . . the pirates of the sky! This pterodactyl-like bird has a forked tail and rarely flaps its wings when it flies. Even though the magnificent frigatebird spends its life flying over the ocean, it doesn’t land on its surface because this bird’s feathers are not waterproof. So how does the magnificent frigatebird eat without getting wet? Well, when it’s not capturing flying fish, this bird snatches other birds’ prey in mid-air!
Alongside the fascinating creatures residing on land and soaring through the skies are the ones equipped with gills and fins—the ones swimming in oceans across the world, navigating the depths in ways that are as mysterious as they are remarkable.
In this blog post, we’ll be taking a closer look at deep sea fish—particularly, bioluminescent fish. They’re like little lanterns in the ocean, lighting the way as they swim in depths we can’t quite fathom so they can thrive, survive, and, well, make us humans marvel at how brightly they glow.
Defining Bioluminescence
First and foremost, let’s define bioluminescence. Bioluminescence indicates that a living organism is capable of producing its own light. According to Monterey Bay Aquarium (MBA), “On land, the phenomenon of bioluminescence is rare — limited to fireflies, some mushrooms, glowworms, and a few other organisms.” In the ocean, however, a study conducted by the Aquarium found that approximately 75 percent of deep-sea animals make their own light.
What’s more, MBA notes that different species display bioluminescence in different ways, writing, “Some have illuminating cells on their sides, the underside of their stomachs, surrounding their mouths, or on the tip of their tentacles. Others release a bioluminescent fluid or ‘bombers’ into the surrounding water. Some animals, like the angler fish, don’t create their own light. Instead, they rely on symbiotic algae (housed inside their body) to do it for them.”
The fact that deep sea fish generate their own source of light is fascinating, especially when you consider how bioluminescence is crucial to their survival.
Life as a Bioluminescent Fish
Light emitted by deep sea fish underscores how they have adapted to life in a part of the sea that’s dramatically different from life near the surface. Fish that swim near the surface of the water use their eyesight to hunt for prey and attract mates, but that’s not the case for deep sea fish; they must use self-generating light and their heightened sense of awareness to navigate their exceptionally dark and rather extreme environment.
Bioluminescence is essentially a survival mechanism for deep sea fish—a way for them to protect themselves from predators, find mates, and secure their next meal. The anglerfish serves as a great example of how a bioluminescent fish captures prey in a part of the sea where food is scarce, to say the least.
A rod that projects from the anglerfish’s head contains a little sac at the end called the esca. The esca is filled with glowing bacteria, so instead of hunting for their prey, anglerfish wait for curious prey to venture toward them. Just like moths and bugs flying toward bright lights, the anglerfish’s prey finds the glowing light quite irresistible and swims straight toward it.
Light travels differently underwater, so bioluminescence is described as being “blue-green” in color due to shorter wavelengths of light. Red light doesn’t penetrate the ocean depths and, yet some deep sea fish, such as the stoplight loosejaw, can emit red light!
The stoplight loosejaw’s bioluminescence is produced by an organ beneath each eyeball. Oceana states that this bioluminescent fish “is named for the two specialized light-producing organs that are located below each eye. One is green and one is red. Producing light in these two colors increases the ability of the stoplight loosejaw to see and attack its prey. The red organ, in particular, is valuable because most species at those depths cannot see red light. A red crustacean, for example, would be easy to see in red light, even if the crustacean cannot sense the light itself.”
Researchers are still learning about bioluminescent fish. Smithsonian Ocean notes, “In fish alone, there are about 1,500 known species that luminesce. This number continues to grow as research makes new discoveries.” Furthermore, their article on the subject highlights that it “has evolved many times over,” as evidenced by “the number of species that produce bioluminescence and the variations in the chemical reactions that produce light.”
Join Harbor Breeze Cruises on a Journey on the Pacific
Next time you turn on a nightlight to produce light in a dark bedroom, we hope you’ll recall this blog post and tell a friend or loved one something you learned about bioluminescent fish.
At Harbor Breeze Cruises, we’re passionate about educating (or should we say “illuminating”?) people like you about the ocean and its inhabitants. We invite you to bookmark this blog page so you can continue reading our exciting blog posts, plus join us for a whale watching cruise next time you’re in California.
Our captain and crew members—not to mention our enthusiastic Aquarium of the Sea educators—are always eager to answer your questions and help you learn about the ocean. As this blog post emphasized, the ocean is home to all sorts of creatures, including bioluminescent fish that are swimming in a deep, dark, and mysterious world. You won’t be able to see deep sea fish on your cruise with us, of course, but there’s a chance you’ll see some magnificent whales and/or dolphins!
You can purchase your tickets online by visiting our website and selecting your preferred departure date and time. Or, if you prefer, you can give one of our friendly staff members a call at 562-983-6880. We’d be happy to help you reserve your tickets for an upcoming whale-watching tour; it’s a great way to spend time on the Pacific Ocean with like-minded adventurers and nature lovers!