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The colors and light of the deep sea are on full display in these photos from The Radiant Sea: Color and Light in the Underwater World. In this dark realm, coral, shrimp, sharks, jellyfish squid, lantern fish, and more use multi-colored lights for self-defense, to lure food, communicate, and attract mates.
Here are just a few of the photos in the new book celebrating these diverse sea creatures. (Click to expand images to full screen.)
Chaetopterus variopedatus – Parchment-tube worms are found most commonly in their cluster of tubes in the mud of shallow sand flats. Each end of the tube sticks above the mud, but the rest of the animal is completely buried. The worm usually shares this dark and likely dreary burrow with a few small crabs. Unusually, for an animal that has almost no one to signal to, this worm has a truly impressive bioluminescent display that consists of both light organs and luminous mucus. Depending on the species, the light can be violet, blue, green, or even yellow, and despite several attempts, no one is sure why the light is emitted at all. The glowing mucus is ejected from the tube like a volcano of light, and may deter settlers from taking up residence in their tube. CREDIT: Sönke Johnsen.Stomias – This fish is one of many in the family known as “the dragon fishes.” They are relatively small, but impressive predators of anything smaller than they are, typically with mouths full of long, sharp teeth. They also appear to use light in multiple ways. This photo shows the bioluminescent organ that hangs from a long stalk below the chin. This organ likely acts not only as a lure, but – because the shapes of the organs vary by species – may also serve as a mating signal for animals that may have no other way of recognizing each other. CREDIT: Steven HaddockStauroteuthis syrtensis – Sönke: As is sometimes said, the sound of discovery is less often “eureka!” and more often “hmm, that’s odd.”I found myself having just such a moment on one of my early research cruises. We had just caught the beautiful octopus shown here and spent an embarrassing amount of time staring at it as it swam around in a homemade circular tank. We then noticed that the suckers on the animal were unusually shiny, too flat, and didn’t have the usual suction-cup depression in the middle. We thought they might be light organs and scurried inside a darkroom to find out. We touched the suckers and they glowed blue in a scintillating pattern. Later, on land, some colleagues of ours showed via microscopy that the suckers had evolved to become light organs, therefore we had caught evolution in “mid-step.” Here the animal is shown in white light, but under these conditions its luminescence is not visible. CREDIT: Sönke Johnsen.Cerianthus – Unlike their rocky-reef cousins, tube anemones live on sandy, soft seabeds and deeper in the ocean—from just below low tide to beyond 3,000 meters. They have a mane of long tentacles around the outside, surrounding a tuft of shorter tentacles at the center of their tube. When something bumps into the tentacles, the anemone will retract with startling speed. Take a look at where fluorescence is brightest in this species; right where you would expect a potential prey item to investigate. We believe that the fluorescent proteins in these anemones are serving to attract prey in their normally dim blue environment. CREDIT: Steven HaddockBathophilus – This formidable fish has been featured in both the Transparency and Iridescence sections, and could have been mentioned in Bioluminescence as well. Here we can admire the fluorescence of its many kinds of photophores. Small diffuse spots cover the body surface, and a green photophore under the eye is used as a headlamp and emergency beacon. (We know this because they flash these lights when wiggling to escape.) What is potentially novel is that this species also has a red light organ under its eye, likely serving the same night-vision function that is found in the dragonfish Aristostomias. CREDIT: Steven Haddock Steven HaddockTetrorchis hydromedusa – The pink pigmentation that is in the canals of this small jellyfish is reminiscent of the canals in Crossota millsae (p. 76). The deep-red gut suggests a similar function to so many others, but the pink color may be a dilute version of the red, especially as it is highlighted by the four bright white gonads attached to the inside of the swimming bell. CREDIT: Steven Haddock Steven HaddockJapetella – Not only does the deep-sea pelagic octopus Japetella exhibit transparency and pigmentation—and wear bioluminescent “lipstick”—but its tissue is embedded with reflective iridescent structures with angle- dependent iridescent color. It is possible in some species that iridescence gives them a low-cost way to break up their silhouette. CREDIT: Steven HaddockFluoresecence – Making light from light.CREDIT: Steven HaddockPlanctoteuthis – The skin of this deep-sea squid is peppered with chromatophores in varying stages of dilation. Although the amount of pigmentation is the same when dilated or contracted, the tiny dense spots are less visible than the expanded but more diffuse patches. CREDIT: Steven Haddock.
Steven Haddock– studies marine diversity, molecular biology, and bioluminescence at the Monterey Bay Aquarium Research Institute and the University of California, Santa Cruz. Documenting creatures in the deep sea and capturing their luminescent displays, many for the first time, he aims to increase an appreciation and understanding of the ocean’s inhabitants. His imagery and research have been featured in National Geographic, the New York Times, and BBC documentaries, among many others. His other books include the manual Scientific Blue-water Diving and the textbook Practical Computing for Biologists.Â
Sönke Johnsen first trained in math and art and has studied light in nature for 33 years, the last 22 of which have been at Duke University. He is particularly interested in vision, signaling, and camouflage in the open sea. His field work primarily involves open-ocean research cruises that use scuba and deep sea manned and robotic submersibles. Johnsen’s research has been featured in the movie Finding Nemo, the Magic Tree House book series, the poetry of John Updike, and the humor of Dave Barry.
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