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Defying Depth - Comments

Misfire's Avatar Comment 1 by Misfire

I've been curious about animals that can survive in both deep and shallow water. Is it only air which would expand or contract when an animal moves up or down? If a person drowned, their lungs filled with water, and they sank a few thousand meters, would they be crushed?

In any case, aren't sperm whales' lungs full of air?

Sun, 03 Jun 2012 20:51:14 UTC | #945349

bluebird's Avatar Comment 2 by bluebird

...scores of strange-looking animals

Wonder if this particular shrimp is included in the Census of Marine Life ~ link text

A recent show about deep ocean/sea exploration lamented the fact that more research vessels are needed; as it is, scientists have to wait their turn (as with large telescopes).

Oh, and pass the cocktail sauce!

Sun, 03 Jun 2012 20:53:06 UTC | #945350

Kim Probable's Avatar Comment 3 by Kim Probable

Comment 1 by Misfire :

I've been curious about animals that can survive in both deep and shallow water. Is it only air which would expand or contract when an animal moves up or down? If a person drowned, their lungs filled with water, and they sank a few thousand meters, would they be crushed?

In any case, aren't sperm whales' lungs full of air?

Studies done with bottlenose dolphins have shown that their rib cages collapse under pressure, by having the dolphin dive and press a button that takes a picture of itself. Once their ribs collapse, they pretty much sink like a rock, and exert little energy in diving. I was trying to find information on whether or not they do a deep dive with full lungs - they may not. Before a long dive, whales and dolphins usually take a few breaths, and they have very efficient lungs that can almost exchange all of the gas within them with each breath. They have more hemoglobin than we do, and they can store more oxygen in their muscles, so they may not need full lungs of air while diving.

Sun, 03 Jun 2012 21:15:51 UTC | #945352

ANTIcarrot's Avatar Comment 4 by ANTIcarrot

"How deep sea creatures, and close relatives, survive tons of water weight."

For the record, an average sea level pressure of 14.1PSI, when converted to metric... 14.1/2.5/2.5/2.2*10,000 = TEN TONS per square meter.

Gee, I wonder how humans survive with TEN WHOLE TONS of ATMOSPHERIC PRESSURE pressed down on EVERY SQUARE METER OF THEIR BODY! Wonder they don't get crushed to death under the weight of all that gas poor things...

Mon, 04 Jun 2012 12:22:16 UTC | #945457

Alan4discussion's Avatar Comment 5 by Alan4discussion

Comment 1 by Misfire

I've been curious about animals that can survive in both deep and shallow water. Is it only air which would expand or contract when an animal moves up or down?

In any case, aren't sperm whales' lungs full of air?

Whales are only vulnerable to "the bends" while their lungs are inflated near the surface. Once their lungs collapse on deep dives they are OK.

http://www.livescience.com/4234-whales-set-deep-diving-record.html - The researchers analyzed the whales by tagging them and recording their sounds and movements. Their data suggest that the greatest risk of decompression sickness stems from dives that occur between depths of 100 to 250 feet.

"The reason for this is that once the lungs have collapsed under pressure, gas does not diffuse from the lungs into the blood," Tyack said. "Lung collapse is thought to occur shallower than 330 feet, so deeper parts of the dive do not increase the risk of decompression problems. However, if beaked whales responded to sonars with repeated dives to near 165 feet, this could pose a risk."

Mon, 04 Jun 2012 16:04:03 UTC | #945495

David-in-Toronto's Avatar Comment 6 by David-in-Toronto

Comment 1 by Misfire :

I've been curious about animals that can survive in both deep and shallow water. Is it only air which would expand or contract when an animal moves up or down? If a person drowned, their lungs filled with water, and they sank a few thousand meters, would they be crushed?

No. Ambient water pressure (like air pressure) is uniformly distributed - unlike, say, the bilateral crushing force of a vise. Also, fleshy bodies are mostly liquid and therefore incompressible.

I assume when deep-sea critters are brought to the surface and “explode,” there’s some expansion of internal gases going on.

Mon, 04 Jun 2012 20:59:58 UTC | #945568

Angelos333's Avatar Comment 7 by Angelos333

I am curious... How do we know the creatures migrated to the depths as opposed to starting in the depths and migrating to the surface? ex. If life started near deep sea vents and evolved to live in less pressure and ultimately the surface.

Mon, 04 Jun 2012 21:50:46 UTC | #945581

Misfire's Avatar Comment 8 by Misfire

Much obliged Kim, Alan and David; I'd never come across that.

I think I can more or less picture how lungs might collapse, and did a quick search: http://www.oocities.org/spirit_of_the_dolphin/anatomydolphin.html

I think it would surprise most people to learn, though, that whales and dolphins breath out before diving. And I guess, being among the politest of mammals (the dolphins anyway), their stomachs refrain from producing any gas? Or does it just not linger?

Mon, 04 Jun 2012 21:59:33 UTC | #945584

ShadowMind's Avatar Comment 9 by ShadowMind

I would tend to agree with Angelos333; I suspect that the shrimp, living in the shallows but able to survive at depth, is a recent (evolutionarily speaking) migrant from the deep to the shallows.

Tue, 05 Jun 2012 00:18:49 UTC | #945614

Alan4discussion's Avatar Comment 10 by Alan4discussion

Comment 7 by Angelos333

I am curious... How do we know the creatures migrated to the depths as opposed to starting in the depths and migrating to the surface? ex. If life started near deep sea vents and evolved to live in less pressure and ultimately the surface.

There seems to be a view that seas on the early Earth were shallow before the continents formed on the crust.

It has been hypothesized that early Earth's shallow seas existed at the very beginnings of life some 3.8 billion years ago. See :-2. Ambient conditions of early life on this link.

Tue, 05 Jun 2012 12:16:34 UTC | #945679