The Deep Sea • Hacker News Board

Re: The Deep Sea

#21

Post by glofish » Sat, Dec 21, 2019, 9:24 PM UTC

jimmyswimmy wrote: post #18

nexuist wrote: post #15

Earlier quoted context omitted.

External pressure. It might be easier for you to survive at 130ft because you have a sturdy rib-cage and skull that keeps your internals together. Fish do not get this luxury. It might be entirely possible for a fish to swim down to 3000 meters, but I think evolution probably played a role in killing off all the fish who decided to risk it and swim that deep. As a result, "modern" fish probably experience more anxiet…

I think this is wrong but I am not a biologist. Fish do not contain air, which is the compressible fluid which limits our ability to go to great depths unprotected. Water is very incompressible, and is most of what fish are. So I don't think depth is the issue. I would hazard a guess that it has to do with where food is.

Fish control their buoyancy via a swim bladder.

Suddenly bringing up a deep water fish would make it explode. every 33ft up the volume of air doubles.

Hence that rule of diving of never holding your breath and continuously letting the air out as you surface.

What I find incredible that a seal could dive that deep, the volume of air at that depth would be a tiny fraction of the volume of air at the surface. It is as if its lungs were completely collapsed and empty.

Re: The Deep Sea

#22

Post by dugmartin » Sat, Dec 21, 2019, 9:25 PM UTC

stared wrote: post #6

It reminds me of another scrolling experience, "If the Moon Were Only 1 Pixel - A tediously accurate map of the solar system" ( https://joshworth.com/dev/pixelspace/pixelspace_solarsystem.... ).

There is a space object size visualization on that same site that is worth a look:

https://neal.fun/size-of-space/

Re: The Deep Sea

#23

Post by greendream17 » Sat, Dec 21, 2019, 9:32 PM UTC

aliceryhl wrote: post #8

Huh, penguins can dive deep.

Yea, that would be like me running to the night-shop to get beer and run back home, all the while holding my breath.

Re: The Deep Sea

#24

Post by skunkworker » Sat, Dec 21, 2019, 9:42 PM UTC

rwmj wrote: post #19

Elephant Seals dive to 2400 meters and Cuviers Whales to 3000 meters? That's incredible for a mammal.

I was amazed at that as well about the Elephant Seal.

"One final note about life in the abyss: not all intruders from the lighted world are ROVs or submarines. A southern elephant seal tagged by Census project TOPP recently dove down 2,388 meters (~1.5 miles) from the surface. At that depth, water pressure is roughly equal to 240 times the air pressure at sea level. The human eardrum can rupture at 10 meters"

http://www.coml.org/comlfiles/press/CoML_Beyond_Sunlight_11....

Re: The Deep Sea

#25

Post by Volker-E » Sat, Dec 21, 2019, 9:48 PM UTC

This is beautiful, thanks. Why not linking the creatures to their English Wikipedia pages to get curious folks more background? Wikimedia Foundation employee here in private comment. Just learnt the first time about the Leatherback Sea Turtle here.

Re: The Deep Sea

#26

Post by lifeformed » Sat, Dec 21, 2019, 9:54 PM UTC

Volker-E wrote: post #25

This is beautiful, thanks. Why not linking the creatures to their English Wikipedia pages to get curious folks more background? Wikimedia Foundation employee here in private comment. Just learnt the first time about the Leatherback Sea Turtle here.

This kind of content reminds me of Microsoft Encarta. It would be really neat if there were lots of visualizations and interactive educational sites that shared many links to Wikipedia, and have them all compiled somewhere on some Wikimedia page.

Re: The Deep Sea

#27

Post by clort » Sat, Dec 21, 2019, 9:57 PM UTC

glofish wrote: post #21

jimmyswimmy wrote: post #18

Earlier quoted context omitted.

I think this is wrong but I am not a biologist. Fish do not contain air, which is the compressible fluid which limits our ability to go to great depths unprotected. Water is very incompressible, and is most of what fish are. So I don't think depth is the issue. I would hazard a guess that it has to do with where food is.

Fish control their buoyancy via a swim bladder. Suddenly bringing up a deep water fish would make it explode. every 33ft up the volume of air doubles. Hence that rule of diving of never holding your breath and continuously letting the air out as you surface. What I find incredible that a seal could dive that deep, the volume of air at that depth would be a tiny fraction of the volume of air at the surface. It is as i…

Yes the lungs are collapsed completely. A seal, as I understand it, has extremely haemoglobin rich blood and stores all its oxygen there for the dive.

Re: The Deep Sea

#28

Post by glofish » Sat, Dec 21, 2019, 9:59 PM UTC

clort wrote: post #27

glofish wrote: post #21

Earlier quoted context omitted.

Fish control their buoyancy via a swim bladder. Suddenly bringing up a deep water fish would make it explode. every 33ft up the volume of air doubles. Hence that rule of diving of never holding your breath and continuously letting the air out as you surface. What I find incredible that a seal could dive that deep, the volume of air at that depth would be a tiny fraction of the volume of air at the surface. It is as i…

Yes the lungs are collapsed completely. A seal, as I understand it, has extremely haemoglobin rich blood and stores all its oxygen there for the dive.

ah, fascinating! now it makes sense, it stores the air somewhere else!

Re: The Deep Sea

#29

Post by Exmoor » Sat, Dec 21, 2019, 10:04 PM UTC

rwmj wrote: post #19

Elephant Seals dive to 2400 meters and Cuviers Whales to 3000 meters? That's incredible for a mammal.

Beaked whales in general are fascinating. Only a fraction of a percent of people will likely every see one and only a fraction of those people will even know that they're seeing something more notable than any other whale. They're incredibly poorly understood to the point where there are very possibly species that are completely unknown to science.

https://en.wikipedia.org/wiki/Beaked_whale

Re: The Deep Sea

#30

Post by LeifCarrotson » Sat, Dec 21, 2019, 10:07 PM UTC

nexuist wrote: post #15

alister wrote: post #10

I wonder what prevents a fish that goes down to 100 meters from going down to 300 meters or 3000 meters. Does it feel an internal pressure that tells it to not dive further, or is it the amount of light or availability of food it seeks? Since fish wouldn't suffer from decompression sickness, I wonder if they could dive much deeper if they wanted to. Now that I think about it, I've scuba dived to 130 feet and it didn'…

External pressure. It might be easier for you to survive at 130ft because you have a sturdy rib-cage and skull that keeps your internals together. Fish do not get this luxury. It might be entirely possible for a fish to swim down to 3000 meters, but I think evolution probably played a role in killing off all the fish who decided to risk it and swim that deep. As a result, "modern" fish probably experience more anxiet…

This is not correct. Your rib cage and skull are scarcely able to contain the immense pressure at 130 ft. When SCUBA diving, you inhale air at the same pressure as the water at your current depth, there's no force on your rib cage. When free diving, your flexibility allows your organs to compress into the space previously occupied by your lungs.

A fish's swim bladder is full of air that's been extracted from the water. As long as they don't go up and down too fast, they'll be fine at whatever depth.

But the other side of the equation is the partial pressures of various gasses dissolved in the blood. Humans experience nitrogen narcosis and oxygen toxicity just from breathing regular air and need special mixtures, fish need special biology to cope.