Starship Asterisk*

Ann wrote:
And Art, I just love that info about the names of different depth layers of the ocean. The names of the top two layers don't tell me much, although I appreciate the pretty color of them - well the pretty color of the layers, not the names. (Perhaps the top one should be called cyanopelagic, or even caerulopelagic?) But the third: Bathypelagic! Where you take bath? And the fourth: Abyssopelagic. Okay, now we're in the abyss! And the fifth, although it's more of a crack than a layer: Hadopelagic. We've finally come to Hades!

https://en.wikipedia.org/wiki/Mariana_Trench#Descents wrote:
<<The Mariana Trench or Marianas Trench is the deepest part of the world's oceans. It reaches a maximum-known depth of 10,994 metres at a small slot-shaped valley in its floor known as the Challenger Deep, at its southern end(, although some unrepeated measurements place the deepest portion at 11,034 metres). The first manned descent was by Swiss-designed, Italian-built, United States Navy-owned bathyscaphe Trieste which reached the bottom at 1:06 pm on 23 January 1960, with Don Walsh and Jacques Piccard on board. The second (and last) manned descent was 52 years later made by Canadian film director James Cameron in 2012. On 26 March, he reached the bottom of the Mariana Trench in the submersible vessel Deepsea Challenger.>>

Chris Peterson wrote:

neufer wrote:

Chris Peterson wrote:
The effect you saw was probably caused by dinoflagellate luciferin, not coelenterazine. Both are blue (marine bioluminescent chemistry has almost all evolved to produce blue light, since it travels farther in water), but the former is associated with glowing from waves and other disturbed water.

• It's a good thing that Ann didn't go swimming below a depth of 500 meters:

Why would she? It's black down there, not blue. She wouldn't waste her time on it!

https://en.wikipedia.org/wiki/Mesopelagic_zone wrote:

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<<The mesopelagic (Greek μέσον, middle) (also known as the middle pelagic or twilight zone) is that part of the pelagic zone that extends from a depth of 200 to 1000 metres below the ocean surface. It lies between the photic epipelagic above and the aphotic bathypelagic below, where there is no light at all.

Although the temperature varies less at any one height than the epipelagic, the mesopelagic is the location of the thermocline; and in warmer regions of the world, the temperature varies from over 20°C at the top to around 4°C at the boundary with the bathyal zone. Water generally moves slowly in the mesopelagic with a residency time of about a century though a variety of animals move vertically through the zone on a daily basis and various debris sink down in relatively short time frames.

Although some light penetrates the mesopelagic zone, it is insufficient [and too blue] for photosynthesis. The general types of life forms found are daytime visiting herbivores, detritivores feeding on dead organisms and fecal pellets, and carnivores feeding on the former types. Examples of animals in the mesopelagic zone are: bristlemouth, swordfish, squid, wolf eels, cuttlefish and other semi-deepsea creatures. The bristlemouth is the Earth's most abundant vertebrate, numbering in the hundreds of trillions to quadrillions. The small amount of sunlight is sufficient for animals, such as the chain catshark, to be fluorescent.

The quantity of mesopelagic life is large enough to play a significant role in global carbon cycling. As the fish participate in the food chain, they acquire carbon rendered from carbon dioxide absorbed by surface waters. Upon death, they transport that carbon into the abyss. As of 2015 the revised estimates of mesopelagic life had yet to be incorporated into climate models.>>

neufer wrote:

Chris Peterson wrote: The effect you saw was probably caused by dinoflagellate luciferin, not coelenterazine. Both are blue (marine bioluminescent chemistry has almost all evolved to produce blue light, since it travels farther in water), but the former is associated with glowing from waves and other disturbed water.

• It's a good thing that Ann didn't go swimming below a depth of 500 meters:

Chris Peterson wrote:
The effect you saw was probably caused by dinoflagellate luciferin, not coelenterazine. Both are blue (marine bioluminescent chemistry has almost all evolved to produce blue light, since it travels farther in water), but the former is associated with glowing from waves and other disturbed water.

• It's a good thing that Ann didn't go swimming below a depth of 500 meters:

https://en.wikipedia.org/wiki/Stoplight_loosejaw wrote:

[b][color=#0000FF]Malacosteus uses its suborbital photophores like searchlights to find prey.[/color] [color=#FF0000]Beneath the eye is a teardrop-shaped photophore that emits red light.[/color] [color=#00AF00]Behind it is an ovoid postorbital photophore that emits green light.[/color] [color=#0000FF]These red and green photophores are evocative of traffic lights.[/color][/b]

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<<The stoplight loosejaws are small, deep-sea dragonfishes of the genus Malacosteus. They are found worldwide, outside of the Arctic and Subantarctic, in the mesopelagic zone below a depth of 500 meters. Malacosteus and the related genera Aristostomias and Pachystomias are the only fishes that produce red bioluminescence. As most of their prey organisms are not capable of perceiving light at those wavelengths, this allows Malacosteus to hunt with an essentially invisible beam of light. The rapid attenuation of red light in sea water gives Malacosteus a shorter visual range than species that use blue light, and it does not migrate vertically into more productive [Ann filled] waters like other stomiids. Furthermore, Malacosteus is unique amongst animals in using a chlorophyll derivative to perceive red light. No vertebrates are known to synthesize chlorophyll derivatives, and Malacosteus is believed to obtain these derivatives from the copepods it consumes. These fishes have a wide distribution in all oceans: M. niger is found between 66° N and 33° S, except for the Mediterranean Sea, while M. australis is found in the southern transition zone between 25° to 45° S, where it is bound by the Antarctic Circumpolar Current. Both species are usually found below a depth of 500 meters in midwater. They are the only known stomiids that do not seem to conduct significant diurnal vertical migrations.>>

Ann wrote:But okay, I finally found the answer, tucked away far down in one of the Wikipedia articles.

Wikipedia wrote:

It was later discovered that the apoprotein can stably bind coelenterazine and oxygen is required for the regeneration to the active form of aequorin.[21] However, in the presence of calcium ions, the protein undergoes a conformational change and through oxidation converts its prosthetic group, coelenterazine, into excited coelenteramide and CO2.[22] As the excited coelenteramide relaxes to the ground state, blue light (wavelength of 465 nm) is emitted. Before coelenteramide is exchanged out, the entire protein is still fluorescent blue.

Nitpicker wrote:

Ann wrote: By the way, can anyone explain why plankton bioluminescence tends toward blue, whereas the bioluminescence of fireflies is yellow?

Different kinds of luciferin:
https://en.wikipedia.org/wiki/Luciferin

Wikipedia wrote:

Coelenterazine is found in radiolarians, ctenophores, cnidarians, squid, brittle stars, copepods, chaetognaths, fish, and shrimp. It is the prosthetic group in the protein aequorin responsible for the blue light emission.

Wikipedia wrote:

Coelenterazine can be crystallized into orange-yellow crystals. The molecule absorbs light in the ultraviolet and visible spectrum, with peak absorption at 435 nm in methanol, giving the molecule a yellow color.

Wikipedia wrote:

It was also noted during the extraction the animal creates green light due to the presence of the green fluorescent protein, which changes the native blue light of aequorin to green.

Wikipedia wrote:

It was later discovered that the apoprotein can stably bind coelenterazine and oxygen is required for the regeneration to the active form of aequorin.[21] However, in the presence of calcium ions, the protein undergoes a conformational change and through oxidation converts its prosthetic group, coelenterazine, into excited coelenteramide and CO2.[22] As the excited coelenteramide relaxes to the ground state, blue light (wavelength of 465 nm) is emitted. Before coelenteramide is exchanged out, the entire protein is still fluorescent blue.

Ann wrote: By the way, can anyone explain why plankton bioluminescence tends toward blue, whereas the bioluminescence of fireflies is yellow?

Chris Peterson wrote:

MarkBour wrote:Having never seen this phenomenon, I was suspicious that it was only visible with astronomer/photographer tricks to enhance the bioluminescent light. But then I watched a few videos and concluded that it really might look this way to the naked (human) eye. Those of you who have seen blue bioluminescent phytoplankton in the surf in person seem to have confirmed that with your reports. Correct? It seems like something beautiful, worth trying to go experience. One of the closest places to me that I've seen listed is San Diego. Is it highly seasonal, or otherwise difficult to catch? Or is it pretty much any night? Ann, you said it was magical. Did you have any feeling that it was like polluted water, or was it just nice?

I've seen bioluminescent plankton on a number of occasions, on the Southern California coastline, at Catalina Island, and in the Mediterranean. It's bright enough to be visibly blue, but I've never seen anything as bright or saturated as what this image shows. But the Milky Way doesn't show color to the eye, either, but this image is bringing that out. So that tells me that all of the dim phenomena in this scene are being boosted somewhat by the relatively long exposure time. (And the zodiacal light here is very dim- probably borderline naked eye.)

MarkBour wrote:Having never seen this phenomenon, I was suspicious that it was only visible with astronomer/photographer tricks to enhance the bioluminescent light. But then I watched a few videos and concluded that it really might look this way to the naked (human) eye. Those of you who have seen blue bioluminescent phytoplankton in the surf in person seem to have confirmed that with your reports. Correct? It seems like something beautiful, worth trying to go experience. One of the closest places to me that I've seen listed is San Diego. Is it highly seasonal, or otherwise difficult to catch? Or is it pretty much any night? Ann, you said it was magical. Did you have any feeling that it was like polluted water, or was it just nice?

neufer wrote:

Ann wrote:
It glows! It's BLUE!

So THAT explains it.

Ann wrote:
Long ago, I was swimming among bioluminescent plankton. It slid past me and all over me and covered me in little starry points of light. It was magical! It glows! It's BLUE!

Nitpicker wrote:Beautiful APOD. Mars also glows, above and to the left of Venus, within the zodiacal light. The trapezium of four stars below Venus, is the handle of the teapot asterism.