Bioluminescence, Part 2

Bioluminescence is produced by a chemical reaction similar to the one that happens when a glow stick is broken. This reaction releases energy as light. The color of the light that is produced is usually blue or green, but can be red, yellow, or orange, depending on the chemicals used in the reaction. Most animals produce only one color of light, but some fish and worms use two colors of light

Looking for fish beneath cliffs of Laird's Sandstone on Tomales Bay
Photo by Casey Newman, 2011, All Rights Reserved.

Some animals, like fish and shrimp, use photophores, or special organs to produce light. Others, such as jellyfish, have specialized cells scattered over their bodies that glow. Certain species of organisms play host to bioluminescent bacteria, which produce light in exchange for room and board. There are some species of squid that produce bioluminescent ink, which is squirted out as a defense mechanism.  Single celled organisms such as bacteria and dinoflagellates use special compartments in their cell to separate the chemicals that react to produce light, combining the compartments when necessary.

At depths of between 200m and 1000m in the ocean, up to 90% of animals use bioluminescence to blend in with their surroundings. The light that reaches down into those depths is blue-green, and these animals will use bioluminescent photophores (cells or organs that produce light) to match the amount of blue-green light around them, camouflaging themselves.  Other fish that live at those depths produce red light. Many organisms that live that deeply cannot see red light, so the fish that produce it can use the light to see their prey without being seen.  Deeper in the ocean, where conditions are always cold and dark, animals do not need bioluminescence to blend in, but they do use it to attract prey and for communication and courtship. These animals have unique patters of photophores, which may help them to recognize others of their species.

Plainfin Midshipman Fish
Photo copyright Terrence J Fidler, 2006,robots4farms.com

One type of bioluminescent fish, called the plainfin midshipman fish, lives deep in the Pacific Ocean but migrates to the coast in the summer to lay their eggs. These fish are a type of toadfish with no spots or stripes on their dorsal fin. Their photophores are arranged in a U-shape on the underside of their body, and the photophores look like the buttons on a naval officer’s uniform, which is how they get the name midshipman fish. The photophores are used to blend in with the light around them while they are in the ocean, which keeps predators from seeing them from below.

The male midshipman fish returns to Tomales Bay first, digging out a nest in the rocks along the shoreline. The rocks at Nick’s Cove are a favorite spot for these nests. Once there, the males begin to hum to attract females. The hearing of the female midshipman fish is so accurate that they can tell the difference between each male’s hum and find the nest of the hum they like best. Once there, the female will lay her eggs and return to the open ocean. The males fertilize and take care of the eggs, continuing to hum until their nests are full of eggs from many females. The males guard the nest until the eggs hatch and the hatchlings are ready to be on their own.

To hear the plainfin midshipman fish’s hum, visit Discovery of Sound in the Sea: http://www.dosits.org/audio/fishes/plainfinmidshipman/.

Bioluminescence, Part 1

What’s all the fuss about bioluminescence? What IS bioluminescence? 

Sunset over White Gulch on Tomales Bay.
Photo by Casey Newman, 2011, All Rights Reserved. 

It’s the production of light by living organisms. It can be used to attract prey, to communicate, and to help an organism blend in with its surroundings. Bioluminescence is also responsible for the glow that can sometimes be seen on moonless nights in the waters of the ocean. In several places in the world, including our own Bay Area, conditions are perfect for an annual “bloom” of dinoflagellates, a type of single celled organisms that are bioluminescent.

Dinoflagellates are a type of unicellular planktonic organism (whew, what a mouthful). They drift with the currents of the ocean (planktonic), using two whip-like structures (flagella) to move their single-celled selves around a bit. They can photosynthesize, or get energy from sunlight, but some dinoflagellates also eat other, smaller organisms. Most of them have armored plates made of cellulose for a cell wall, which makes them tough for their size (and also beautiful under a microscope). Some dinoflagellate species cause red tides, and release toxins that are harmful to humans. Other species, like the species that is found in Tomales Bay certain times of year, are bioluminescent.

The species of dinoflagellates that bioluminesce operate on a circadian rhythm- they photosynthesize during the day and they only glow at night. Because they only glow when they are jostled, it is theorized that they glow as a defense mechanism. One of their main predators is a type of shrimp, and if they glow when they are about to be eaten, the light will hopefully attract a fish, which will hopefully eat the shrimp. The flash of light may also act as a distraction, blinding the predator to allow the dinoflagellate time to get away.

During certain times of the year, strong winds push the top layer of coastal water offshore, allowing cold, nutrient-rich water to flow up from the ocean floor. This is known as upwelling, and it is responsible for the surge in nutrients that feed an explosion in the population of single celled algae. One species of those algae are the dinoflagellates that produce the light we see on Tomales Bay. Their bioluminescence can occasionally be seen year round, but tends to be strongest in the summer and early fall. The amount of nutrients in the water affects when we can see the bioluminescence and how long it lasts.

The waters of Tomales Bay are a perfect location for viewing the bioluminescence. Tomales Bay has a narrow opening which limits the amount of water that is exchanged during the tides, concentrating the dinoflagelates in the bay. Beds of eelgrass, a plant with long blades, further trap and concentrate the dinoflagellates in the shallow parts of the bay. The northern end of the bay is relatively undeveloped, which keeps light pollution from washing out the flashes of green light when the organisms are moved. 

A paddle through the bioluminescent waters of Tomales Bay is an amazing experience. As we paddle through the water, our boats, paddles, and even hands can jostle the organisms and make them flash. The bioluminescence does not hurt the dinoflagellates, and they can continue to emit flashes of light for hours. On especially dark nights, fish can be seen setting off the bioluminescence as they swim through the waters underneath our boats. The peaceful waters of Tomales Bay provide a protected location filled with wonderful wildlife to paddle past, and the bioluminescence is truly breathtaking.

Sunset on Tomales Bay.
Photo by Casey Newman, 2011, All Rights Reserved. 

Want to know more about bioluminescence? Check out the Bioluminescence Web Page at http://www.lifesci.ucsb.edu/~biolum/, or tune in next week for more information about bioluminescent critters and about a specific type of bioluminescent fish that returns to Tomales Bay every summer.  

Glowing Green Halloween 2010

By Joyce Goldfield -Point Reyes Outdoors Customer

Halloween! What on earth does a 73 year old woman do on Halloween? I’m pretty game-I was going to drag out my old pumpkin costume and limp on down to the local happenings in Point Reyes. Just then the phone rang! Saved!



My friend Laurie, who owns Point Reyes Outdoors kayaking, hiking and biking company, spoke. Her question…

“Hey, we have an extra spot on our kayaking trip tonight. We’re going out on the bay to see the bioluminescence. Want to come?”

“Well, yeah!! I was just trying to get up the enthusiasm to don my pumpkin suit and go trick or treating!” My comment received her familiar laugh…

“Great. Meet me at the office at about 4pm and you can ride up with me. We plan to put in at Nick’s Cove in Marshall at 4:30pm. Wear a fleece and some warm socks. I’ve got everything else for you.”

So I did…and she did! She even brought me some extra socks! We rode up to Marshall, followed by her guide, who was driving the van, pulling a trailer of kayaks. The back of the van was stuffed full of gear.

We arrive at Nick’s Cove, just as the late afternoon serenity and softness was settling over the world. Somehow that time of day always inspires me to talk more softly and breathe more deeply.

Kayaks were unloaded and sat bobbing at the water’s edge, waiting. Customers arrived and Laurie greeted them warmly, quickly assessed our clothing and suggested we don one of her waterproof jackets with Velcro closures at the neck and cuffs. She also gave each of us a pair of warm kayaking gloves and waterproof pants. Over the top of all this was a kayaking spray skirt to keep us snug and dry as we paddled. All this was topped with a comfortable life vest. We looked at one another and giggled. I often spend time on the Bay so am accustomed to dressing in layers, but don’t own any of this waterproof gear – and definitely no spray skirt. I’m usually sopping wet halfway across the bay. Not tonight!!

Casey, the guide, gave each of us an individual brush up lesson on how to hold a paddle, advise on strokes, how to operate the rudder pedals (if you are seated in the stern of a two-person kayak) and some wise advice about giving plenty of room to the wildlife, not approaching close enough to flush them from their resting spots. And we were off!!

Tomales Bay Sunset
Photo by Alia Pasquale

Tomales Bay lay flat calm. I’ve lived here for 35 years and have spent many hours sailing and canoeing on this water. I’ve NEVER seen it like this…a shining sheet of glass! Just enough time had passed for the sunset to be at its most breathtaking. Not only was the sky all shades of pink/purple/orange/red, but this palette was reflected across the water, shore to shore. Floating on this amazingly brilliant canvas were all manner of sea bird: loons, cormorants, pelicans, gulls, ducks, herons. The guide knew facts and lore about all of them, which she happily shared. Remember how still and peaceful I told you it was? Now imagine the single call of a loon, floating across the still waters. Cormorants were making noise similar to an “oink”! Then as we approached Hog Island, in the middle of the bay, seals popped their heads up out of the water to view us as we passed. Many were pulled out on the sand spit of the island. Again, so still, we could hear them burp and scratch! Three very young, curious ones followed us. They kept bobbing their heads up to get a better look with their large dark eyes.

Coming around the island, in the middle of the bay, we saw a strange sight. A great Blue Heron was standing ON the water, not wading near shore, but in the middle of the bay. We gave him a wide berth, but perplexed as we tried to figure out his illusion. Floating near us there was a small cluster of bull kelp, a species seldom seen in the bay, but often found in large piles on ocean beaches. These stragglers could have floated in from the ocean, over the sandbar at the mouth, and into the bay. Seems the Heron was standing on a slightly submerged knot of kelp.

The light was slowly fading as we approached White Gulch, on the opposite shore. We cruised in and out of all the nooks, crannies, and caves along the bluff. They pointed out all manner of sea life: Sea anemones gently swaying their fronds to capture food, gorgeous, graceful brown jellyfish pulsing their way along in calm waters, bright star fish and one ethereal white moon jelly. The guide explained that river otters often hang out by the small caves near the bluff.

We paddled toward a small white beach and we pulled ashore. Laurie and the guide pulled out a table and a delightful repast of grapes, chocolate cherry cookies, almond pastries, a three-fruit buckle, and best of all, mugs of steaming hot chocolate.

The night sky was upon us and millions of stars were blooming in the black velvet. Because the water was so calm, every star was reflected therein. Our entire world – sky and water – was a tapestry of golden lights. Behind us, one single elk stood on the hill, silhouetted against the waning light. A huge lone, silent owl flew over us, so low you could feel the rush of the wind from his wings. Having just recently lost my beloved, I smiled, assuming it was his spirit, wishing us well.

Returning to the kayaks, the instant my paddle touched the water, I gasped. I was paddling in molten mercury! In quick silver! I thrust my hand into the water: gloves, jacket and all, wet, just to stir the water with my hand. Everyone was doing the same. We had been conversing in whispers. Not anymore. Everyone was uttering “oohs” and “ahhs” of delight! Then, it got better! EVERYTHING beneath the water was etched in silver and neon green! We could see the sea lettuce and kelp sway beneath. Big, little, wee tiny fish, swimming this way and that…shooting past us, beneath us, in front of us…leading us on their path of silver and brilliant green. Behind us, our wakes were a trail of silver. I scooped up a paddle full of glowing sea lettuce and dropped it back into the water, in a shower of sliver – and laughed aloud.

There was no reason to hurry. We were allowed to wander about (everyone had a red glow stick attached to their kayak for safety). We separated, came together, separated, awestruck!! Where to look? The star strewn black velvet sky? The silver and neon streaked bay, glittering with reflected golden stars? Somehow, it all blended together, it was difficult to see where the horizon line actually was. We were drifting and rotating in a gigantic illuminated bubble. Nobody wanted the evening to end.

As we slowly made our way across Tomales Bay, past the sleep murmurs of the critters on the darkened Hog Island, to the landing at Nick’s Cove…thoroughly relaxed, enchanted, soul satisfied, spirit uplifted, and completely mesmerized by the peace and beauty of it all.

I think I can safely say, that none of us will ever forget this evening as long as we live. None of us will be swept up in life to the extent that this evening doesn’t still dance behind our eyes…in our souls.