The Bioluminescence of Costa Rica

The toucans, sloths, monkeys, macaws, whales and blue morpho butterflies get the glory. These creatures are special in their own ways. But Costa Rica is also rich in another type of natural wonder – its creatures of bioluminescence. Her oceans, beaches and jungles teem with glowing life. Beetles, fungi, jellyfish, plankton, and other forms of life turn our land into a nighttime Pandora. All you need is to open your eyes and really look around!

✨🪰 FIREFLIES

The fireflies of Costa Rica (actually they are beetles) are truly amazing. As the sun dips below the horizon, their faint streaking glows become brighter and numerous. You’d be right to think you are seeing supernatural being or fairies. These glowbugs are the country’s most enchanting creatures of bioluminescence.

I have seen the green ones and the impressive orange ones. The orange fireflies are extremely bright and we have confused them for distant car tail lights and runners’ head torches. This glow serves multiple purposes: attracting mates, deterring predators, and communicating across species lines in the dense underbrush.

To view this wonder in Costa Rica head to warm, low & humid areas – the Ojochal & Costa Ballena surrounds fit that bill perfectly. Especially look for areas near marshes, rivers, lakes – the bugs need constant moisture to survive. For the best experience, choose a site away from lights and explore during dusk and early darkness. Allow your eyes at least 20 minutes to adjust. And aim to be out between May and September – the rainy season. This is the ideal time to see these critters. Remember to ask the locals for best viewing spots – they should know.

✨🌊 THE GLOWING OCEAN

Experiencing this phenomenon will leave you speechless – and in total awe. Imagine entire waves lighting up in bright electric blues. And as you step into the ocean, the water disturbed by your body takes on the enchanted bluish glow. The photos do not do justice to this experience – not even close!

Tiny plankton—dinoflagellates—create the glow. They emit light to startle predators and, during pursuit, attract animals that hunt their attackers. Mechanical disturbance triggers a brief (0.1 sec) blue flash. Boats, swimmers, or waves stir the water and release a sparkling blue light from the sea’s surface.

To see this wonder in Costa Rica, head out  during the dry season (Nov–Apr). Best conditions are those with moonless nights, warm temperatures and calm waters. Calm bays of the Pacific provinces – Guanacaste, Nicoya & Puntarenas – all welcome the glowing plankton at different times. Montezuma area & Paquera Bay, on Nicoya Peninsula, are amongst the top bioluminescence destinations. And the calm, dark bays of Golfo Dulce & nearby Corcovado NP and other protected areas are especially abundant in the glow. This is because these areas are remote & protected, which helps preserve the delicate ecosystems that support bioluminescent plankton. They are also free from most light pollution, which highlights the glow of the ocean. Many tourist operators specialize in, or offer, bioluminescent ocean tours.

✨🍄‍🟫 MUSHROOMS

Luminous fungi are found growing on decaying wood, leading to the popular name of “foxfire” or “glow wood” when their glow is visible at night. Tiny mycelium threads illuminate the wood in an eerie light while the glowing fruiting body paints a magical scene.

Some researchers propose that fungal bioluminescence attracts bugs to spread spores. No one has directly observed this. In many species, only the mycelium glows—not the fruit body—challenging that idea. Hydrated mycelium emits more light, possibly drawing animals that carry spores to moist, growth-friendly areas. Most fungi need moisture to develop.

✨🪱 GLOW WORMS

There are many critters with that name, and not all are worms! Firefly larvae and Railroad Worms are the most famous and common Glow Worms to be found in our area.

Railroad Worms have multiple spots of bioluminescence. Two rows of pin-point yellowish lights along their bodies, and larger glowing areas around the head. The lights around the head often glow in a reddish hue – very unusual. And the rows of pin-point lights resemble illuminated train carriage windows – hance the name.

Firefly larva emit a steady, non-blinking glow from a light organs near the tail or head. These larvae are voracious predators, feeding on snails, slugs, earthworms, and other soft-bodied invertebrates. They inject digestive enzymes into prey, liquefying it before consumption—a surprisingly brutal tactic for such a gentle glow.

Humid moonless nights, especially after decent rains, are the best times to see these critters. Look for shady, wet, undisturbed habitats rich in leaf and decaying wood matter. Head into areas that are far from artificial lights and develop your night vision before entering forests.

✨🐟 FISH

The mysterious Flashlight Fish spends the days in deep waters but, come night, rises up to the shallower reefs. It has two light organs under its eyes. These organs can be ‘shut off’ – by being drawn into the body or by the use of an ‘eyelid’ type of device.

Several other bioluminescent fish call Costa Rica home, but they live at great depths – these are the Lanternfish and Hatchetfish.

✨🪼 JELLYFISH

The Moon Jellyfish frequents our shores and may at times emit a soft pink and bluish glow. They swim with ocean currents  prefer to hang close to shorelines. These jellies are amazing in another way – they are one of very few animals that can regenerate themselves and even reverse aging!

Moonless nights during the dry season – November to April – are the best times to look for these critters. Best places to see these jellies are the same places where the glowing plankton is plentiful – quiet, protected, calm and dark bays of Costa Rica’s Pacific coast.

✨🦐 SHRIMP

We have glowing shrimp. And ones that vomit up a cloud of glowing water to startle predators! Though don’t count on seeing the Heterocarpus shrimp- they live in deeper ocean waters.

In addition, various species of Ostracods & Copepods, which are shrimp-like crustaceans, can be found off the coasts of Costa Rica. These critters emit bioluminescence during courtship displays.

✨🪰 CLICK BEETLES

Emitting continuous light that is bright enough to read by, these insects are often called ‘headlight beetles’. It is thought that dozens of species make Costa Rica home. The have two glow organs just behind the head and a third, larger one on their abdomens. This third light organ is only visible when the beetle is in flight.

These critters are unusual – as unlike the glowing worms, fireflies and fungi, they prefer DRY environments. So look for them around tropical dry forests in northern areas such as Guanacaste including Nicoya Peninsula. They are attracted to light and are often seen circling lampposts.

✨🌒THE MYSTERY OF BIOLUMINESCENCE

Despite its widespread use, bioluminescence remains fairly mysterious. Scientists still don’t fully understand how it evolved or why it’s absent in freshwater ecosystems. What’s clear is that this glowing adaptation has emerged independently in dozens of species, making it one of nature’s most enchanting and versatile traits.

🧐 Fun Facts:

• In 1918, a German U-boat sunk after disturbing bioluminescent plankton off the coast of Spain. The glowing wake betrayed its position to a British ship.
• Japanese army collected large quantities of the bioluminescent Ostracod crustacean from the ocean to use as a convenient light for reading maps and other papers at night. The light, called umihotaru in Japanese, was sufficient to read by but not bright enough to give away troops’ position to enemies.
• Astronaut Jim Lovell once used bioluminescence to locate his aircraft carrier after a failed navigation system. He turned off cabin lights and followed the glowing wake of the USS Shangri-La.
• Many fish use counterillumination—they glow on their undersides to match faint light from above, making them invisible to predators below.
• Before the development of the safety lamp for use in coal mines, dried fish skins were used in Britain and Europe as a weak source of light. It is disputed whether the skin glowed via bioluminescence (for example due fungi or bacteria present) or via reflection of distant lights.
• The molecule responsible for all bioluminescence is called luciferin, from Latin lucifer meaning “light-bringer.” It shares etymology with the name for the morning star—and yes, the theological reference too.
• Bioluminescence has evolved, independently, over 40 times. And as far back as 540 million years ago!

Imagine living in a paradise where surreal glowing oceans add to the already exceptional alure, majesty, wonder & mystery! This land is a true Pandora, ripped from the frames of the famous movie – but it is REAL and WAITING FOR YOU!  RE/MAX WE SELL PARADISE is your trusted real estate partner – while you browse the hundreds of properties available in our area, we are waiting for your call! 

Cover Photo c/o Chasing Lyu, Pexels.