Kurzgesagt – In a Nutshell
Sources
Deep Sea
We would like to thank following experts for their scientific support:
- Paul H Yancey
Senior Research Scientist and Emeritus Professor of Biology.
- Dr. Astrid Leitner
University of Hawaii Manoa, Department of Oceanography.
Sources
– It is hard to believe that less than 2% of all biomass on Earth lives here.
#Personal communication 2018:
Paul H Yancey, Senior Research Scientist and Emeritus Professor of Biology.
#The biomass distribution on Earth, 2018
http://www.pnas.org/content/115/25/6506
Comment: All the subsurface microbes, living in the deep rock beneath our feet are not included in this calculation.
– And of this small percentage around 90% is located close to the surface in the first 200 meters.
#Environmental conditions affecting the sea, 2009
https://www.sciencelearn.org.nz/resources/141-environmental-conditions-affecting-the-sea
Comment:
The source says 150m, but life is possible all over the photic zone, which reaches down to 200m.
– Phytoplankton makes up the foundation for the oceans ecosystem.
#Phytoplankton, 2019
https://en.wikipedia.org/wiki/Phytoplankton
#Role of Algae in the Ecosystem, 2017
https://sciencing.com/role-algae-ecosystem-5819698.html
– The seafloor at this depth is akin to the amazon rainforest.
#Coral Reefs, retrieved 2019
https://marine-conservation.org/what-we-do/program-areas/coral-conservation/coral-reefs/
#Coral Reefs: Canaries of the Sea, Rainforests of the Oceans, 2013
– We reach the end of the continental shelf where we face the continental slope.
#Open Ocean, 2016
https://www.nps.gov/subjects/oceans/open-ocean.htm
#Oceanic basin by Chris_huh, 2007
https://commons.wikimedia.org/wiki/File:Oceanic_basin.svg
– With every additional metre of water, light fades drastically.
#The deep sea, 2018
https://ocean.si.edu/ecosystems/deep-sea/deep-sea
– Humanities deepest scuba dive reached 332 meters.
Comment: There are special pressure suits, which are used for working in the waters close to offshore platforms. These suits look a bit like an armour and allow dives up to 450 m of depth.
#Ahmed Gabr breaks record for deepest SCUBA dive at more than 1,000 feet, 2014
– The pressure equivalent of having over 200 cars stacked on top of you.
Comment:
Here we had to calculate a bit ourselves, because dumping cars on divers (for some strange reason) is a field not many papers cover.
Of course the number of cars weighing on our diver changes, depending on what type of cars you use for the calculation. Here we chose a car with a medium weight.
Pressure is measured in force per area. So the force applied to you when diving depends on the area you are exposing. For simplification, we assume the effective area subject to water pressure is 1 m² per human.
Now for our formula:
Let x be the amount of heavy objects we're looking for, w their average kgs, y the amount of bars (pressure).
x * w * kg * gravitational constant / m² = y bar
⇔ substitute Earth's gravitational constant g ≅ 9.81 m / s² (acceleration), definition of 1 bar = 100,000 N / m² (N = Newton, the unit of force)
(x * w * kg * 9.81 m / s²) / m² = y * 100,000 N / m²
⇔ substitute definition of N = 1 kg * m / s², write units together
x * w * 9.81 * (kg m) / (s² m²) = y * 100,000 * (kg m) / (s² m²)
⇔ divide both sides by ((kg m) / (s² m²)) to get rid of units
x * w * 9.81 = y * 100,000
⇔ divide both sides by w * 9.81
x ≅ 10,193 * y / w
Substituting the weight of a heavy object for w and the pressure in bar for y, we get:
Mid-weight cars (1,500 kg) at deepest scuba dive (332 m, roughly 35 bar):
x = 10,193 * 35 / 1,500 ≅ 238
As we're using simplifying assumptions and averages are somewhat arbitrary, we rounded to 200.
– Actually many fish and other animals spend at least half their lives down here.
#Large mesopelagic fishes biomass and trophic efficiency in the open ocean, 2014
https://www.nature.com/articles/ncomms4271
Summary of study:
#Deep Ocean Harbours 95% Of All Ocean Fish,204
https://www.iflscience.com/environment/deep-ocean-harbours-95-all-ocean-fish/
– Over 90% of the species indigenous to this deep environment use bioluminescence chemicals.
#Bioluminescence, 2018
https://en.wikipedia.org/wiki/Bioluminescence
# Paul H Yancey, Senior Research Scientist and Carl E. Peterson Emeritus Professor of Biology, 2018
Personal communication
– At around 700 meters, we encounter a colony of siphonophores.
#Siphonophores, 2005
http://www.siphonophores.org/index.php
– Most species living down here have to rely on an unlikely ressource: Marine snow.
#What is marine snow?, 2018
https://oceanservice.noaa.gov/facts/marinesnow.html
#Characteristics, dynamics and significance of marine snow, 1988
https://www.sciencedirect.com/science/article/pii/0079661188900535
– Sperm whales hunt and attack giant squids the size of a house.
#Giant Squid. Architeuthis dux, 2018
https://ocean.si.edu/ocean-life/invertebrates/giant-squid
#How Whales Attack Squid: Mystery Deepens, 2007
https://www.livescience.com/7297-whales-attack-squid-mystery-deepens.html
– As we reach 1000m, deeper than the tallest structure built by humans.
#List of tallest buildings and structures, 2018
https://en.wikipedia.org/wiki/List_of_tallest_buildings_and_structures
– This is the midnight zone, a place of absolute darkness.
#Pelagic zone, 2018
https://en.wikipedia.org/wiki/Pelagic_zone
#Open Ocean, 2016
https://www.nps.gov/subjects/oceans/open-ocean.htm
– Like the 30 cm long vampire squid that floats through the water without motion.
#What the Vampire squid really eats, 2012
https://www.youtube.com/watch?v=X8oWnbcLI40&feature=youtu.be&t=33s
#MBARI researchers discover what vampire squids eat (it’s not what you think), 2012
https://www.mbari.org/mbari-researchers-discover-what-vampire-squids-eat-its-not-what-you-think/
Comment: The squids extend just one of their two long catching arms at a time, called filament. So you usually don’t see both arms in the water.
– They are covered in tiny stiff hairs, which “brush” food from the water.
#Vampire squid: detritivores in the oxygen minimum zone, 2012
http://rspb.royalsocietypublishing.org/content/early/2012/09/13/rspb.2012.1357
– Like the viperfish which uses its long fangs to trap even large prey and swallow it whole.
#MOCNESS Monsters: Creatures of the Deep Sea, 2018
https://blogs.nasa.gov/earthexpeditions/2018/09/07/mocness-monsters-creatures-of-the-deep-sea/
– Or the frilled shark with its impressive set of 300 teeth which are recurved backwards.
#Frilled shark, 2018
https://en.wikipedia.org/wiki/Frilled_shark
– We sink further, below the 3,800m mark, as deep as the grave of the Titanic.
#RMS Titanic, 2019
https://en.wikipedia.org/wiki/RMS_Titanic
– The dumbo-octopod, paddling with its ear-like fins.
#Mesmerizing, rare dumbo octopus filmed in the deep sea, 2018
https://www.nationalgeographic.com/animals/2018/10/dumbo-octopus-monterey-seamount-news/
#Everything You Need to Know About the Dumbo Octopus, 2018
https://oceanconservancy.org/blog/2018/10/08/everything-need-know-dumbo-octopus/
– The grenadiers fish with its slow eel like tail beats.
#8 of the Coolest Inhabitants of the Mariana Trench, 2018
http://awesomeocean.com/top-stories/8-coolest-inhabitants-mariana-trench/
– At 4000 m we finally reach ground again: the abyssal plain.
#Pelagic zone, 2018
https://en.wikipedia.org/wiki/Pelagic_zone
#Open Ocean, 2016
https://www.nps.gov/subjects/oceans/open-ocean.htm
#Oceanic basin by Chris_huh, 2007
https://commons.wikimedia.org/wiki/File:Oceanic_basin.svg
– The last remains of marine snow is consumed by sea cucumbers, shrimp, sea urchins or sea worms.
#Feast and famine on the abyssal plain, 2013
https://www.mbari.org/feast-and-famine-on-the-abyssal-plain/
– Small, dark mineral deposits can be seen. These are manganese nodules.
#Manganese nodule treasures, 2014
https://worldoceanreview.com/en/wor-3/mineral-resources/manganese-nodules/
#New Species of Sponges Found on the Pacific Seafloor, 2017
https://www.nytimes.com/2017/10/05/science/sponges-species-pacific-ocean.html
– Magma heats up seawater and creates dark jets of water and minerals.
# Paul H Yancey, Senior Research Scientist and Carl E. Peterson Emeritus Professor of Biology, 2018
Personal communication
#Images: Deep-Sea 'Black Smoker' Vents in Action, 2018
https://www.livescience.com/31437-images-deep-sea-black-smoker-vents-action.html
– Extremophile bacteria use the minerals to create organic substances.
#Earth Life May Have Originated at Deep-Sea Vents, 2013
https://www.space.com/19439-origin-life-earth-hydrothermal-vents.html
#The Biological Deep Sea Hydrothermal Vent as a Model to Study Carbon Dioxide Capturing Enzymes, 2011
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111178/
– Let us enter the hadal zone, the underworld of the sea.
#Pelagic zone, 2018
https://en.wikipedia.org/wiki/Pelagic_zone
#Open Ocean, 2016
https://www.nps.gov/subjects/oceans/open-ocean.htm
#Oceanic basin by Chris_huh, 2007
https://commons.wikimedia.org/wiki/File:Oceanic_basin.svg
– It consists of long narrow trenches that only make up around 0.25% of the oceans.
#All About Trenches, 2014
https://web.whoi.edu/hades/all-about-trenches/
– Like the Etheral snailfish that holds the record for the deepest living fish ever seen around 8000 m.
#Isolation and characterization of type I antifreeze proteins from Atlantic snailfish (Liparis atlanticus) and dusky snailfish (Liparis gibbus), 2001
https://www.sciencedirect.com/science/article/pii/S016748380100190X?via%3Dihub
#Deepest Fish Ever Recorded —Documented at Depths of 8,178 m in Mariana Trench, 2017
https://www.jamstec.go.jp/e/about/press_release/20170824/
– Gently sloping sides enframe a valley of about 1.6 kilometers wide.
#Diving Back To The Bottom Of The Mariana Trench, 2012
https://www.npr.org/2012/03/09/148317355/film-director-to-travel-to-bottom-of-mariana-trench
– The deepest point: The challenger deep. 11000 meters below the surface.
#Mariana Trench, 2018
https://en.wikipedia.org/wiki/Mariana_Trench
#So, How Deep Is the Mariana Trench?, 2014
http://ccom.unh.edu/sites/default/files/publications/Gardner-et-al-2014-Challenger-Deep.pdf
#Mariana Trench: The Deepest Depths, 2017
https://www.livescience.com/23387-mariana-trench.html
– Water pressure here is 1,086 bar. It’s like balancing 1,800 elephants on top of you.
Here we also had to calculate a bit ourselves, since for some reason people don’t stack elephants in deep water. We present the easy and the elaborate version of our calculation:
Easy:
1 African elephant = 6.000 kg
Pressure Challenger Deep: 1.086 bar = 11.074.118,07 kg/m2
11.074.118,07 kg/m2 : 6.000 kg = 1.845,6 kg/m2
#African Elephants, 2019
http://wwf.panda.org/knowledge_hub/endangered_species/elephants/african_elephants/
#Mariana Trench, 2019
https://en.wikipedia.org/wiki/Mariana_Trench#cite_note-6
Since things like water pressure and elephant weights can vary a lot, we rounded our number to 1,800.
Professional:
Pressure is measured in force per area. So the force applied to you when diving depends on the area you are exposing. For simplification, we assume the effective area subject to water pressure is 1 m² per human.
Now for our formula:
Let x be the amount of heavy objects we're looking for, w their average kgs, y the amount of bars (pressure).
x * w * kg * gravitational constant / m² = y bar
⇔ substitute Earth's gravitational constant g ≅ 9.81 m / s² (acceleration), definition of 1 bar = 100,000 N / m² (N = Newton, the unit of force)
(x * w * kg * 9.81 m / s²) / m² = y * 100,000 N / m²
⇔ substitute definition of N = 1 kg * m / s², write units together
x * w * 9.81 * (kg m) / (s² m²) = y * 100,000 * (kg m) / (s² m²)
⇔ divide both sides by ((kg m) / (s² m²)) to get rid of units
x * w * 9.81 = y * 100,000
⇔ divide both sides by w * 9.81
x ≅ 10,193 * y / w
Substituting the weight of a heavy object for w and the pressure in bar for y, we get:
Elephants (average African bush elephant: 6,000 kg) equivalent to Challenger Deep (1086 bar):
x = 10,193 * 1,086 / 6,000 ≅ 1,845
As we're using simplifying assumptions and averages are somewhat arbitrary, we rounded to 1,800.
– Next to sea cucumbers, white and light pink amphipods wiggle their way through the water.
#What does it take to live at the bottom of the ocean?, 2015
http://www.bbc.com/earth/story/20150129-life-at-the-bottom-of-the-ocean
#Deep-Sea, Shrimp-like Creatures Survive by Eating Wood, 2012
#What Lives at the Bottom of the Mariana Trench? More Than You Might Think, 2013
– Plastic bags that were found by scientists in 2018.
#Human footprint in the abyss: 30 year records of deep-sea plastic debris, 2018
https://www.sciencedirect.com/science/article/pii/S0308597X17305195#
#Synthetic polymers in the marine environment: A rapidly increasing, long-term threat, 2008
https://www.sciencedirect.com/science/article/pii/S001393510800159X
Further reading:
– Why do humans struggle to dive deep?
#How do deep-diving sea creatures withstand huge pressure changes?, 2002
https://www.scientificamerican.com/article/how-do-deep-diving-sea-cr/
#If a giant squid has a soft body, how can it survive in such deep water pressure, when even the best submarines can't got as deep that deep?, 2004
http://scienceline.ucsb.edu/getkey.php?key=685
#High Pressure in the Deep Ocean, 2017
https://www.sciencefriday.com/educational-resources/high-pressure-in-the-deep-ocean/
– Deep sea gigantism
#Bergmann’s rule, 2018
https://en.wikipedia.org/wiki/Bergmann%27s_rule
(Larger size in cold area animals because much volume meets relatively smaller surface. In warm climate it’s the other way round to lose warmth faster)
#Faunal diversity in the deep-sea, 1967
https://www.sciencedirect.com/science/article/pii/0011747167900290
#Abstract and Bio: Census of the Diversity of Abyssal Marine Life (Dr. Craig Smith), 2009
– Why bringing deep sea fish to the suurface is not a good idea
#The Physics of . . . Deep-sea Animals, 2001
http://discovermagazine.com/2001/aug/featphysics
#Under Pressure: Will Deep-Sea Animals Explode or Implode on the Surface?, 2016
http://www.deepseanews.com/2016/03/under-pressure/