[Matt Paine]

Matt Paine  asked the Naked Scientists:
   
Greetings from the Gold Coast Australia.

Only been listening to your show for a few months, but I'm catching up on new and old episodes through the podcasts. I have just listened to your podcast originally broadcast on the 25 April 2006 which spoke about the "Cartesian Diver". Your guest on the day, Dr Ron Douglas, explained why deep sea fish didn't explode when they were bought to the surface (as they do not have any air pockets that could expand to explode).

I was wondering what would happen if you took these fish into outer space? Ignoring the lack of oxygen to survive (I assume fish get their oxygen from the water they are swimming in) for the time being, does this mean that fish would survive unprotected in outer space, compared to humans?

My apologies if this has come up before


Thank you for your time.


Matt

What do you think?

[Atomic-S]

I believe the question has to do with the expansion of air and of water. If an organism containing no free air is brought up from the deep, the pressure has dropped enough for that air to expand, if it existed, but it does not. (Although you would think that dissolved gasses could, as with divers that surface too quickly.  Maybe this does happen, but is not expansive enough to produce an obvious external effect.) The pressure has also been reduced on the water, allowing it to expand greatly if only it were hot enough, but it is not.  However, if the organism is then taken to the vacuum of space, the pressure is reduced enough that water can boil, under which circumstances I would expect to see some serious bloating.

[evan_au]

deep sea fish didn't explode when they were bought to the surface

"Exploding" is not the only cause of fish mortality.

I understand that live samples  of deep sea marine life brought to the surface do not survive very long at the pressures found at the surface. Presumably scientists studying the ocean would know how to simulate temperature and oxygen content, so it must be something else.

They would survive even less well in outer space - but the change in pressure from the deep ocean to the surface of the ocean is much greater than the change in pressure from the surface to space.
- From surface to space: 1 atmosphere (100kPa)
- As you go down in the ocean, pressure increases by 1 atmosphere for every 10m of depth. Deep ocean creatures at several km experience pressures of  100s of atmospheres of pressure.

[puppypower]

Water changes properties under pressure. It also changes properties with changing temperature. While the properties of the water impact life. The deep ocean life has unique water properties acting on it. With the oceans, the temperature drops as we go deeper, while the pressure increases as we go deeper. These have opposite impacts on the properties of water.

One artifact of this is the SOFAR Channel; The SOFAR channel (short for Sound Fixing and Ranging channel), or deep sound channel (DSC), is a horizontal layer of water in the ocean at which depth the speed of sound is at its minimum.

There is where increasing pressure and decreasing temperature create a unique water property, where the speed of sound in water reaches a minimum. If you use sonar, the SOFAR channel is like a wall that will reflect the ping. Below the channel is a good hiding place if you need to be stealthy.

Getting back to the deep water critters, if they leave the deep water, the water properties will change, which will have an impact on many of their body systems. The ratio of covalent to polar hydrogen bonding in water changes and can impact the evolved carbon compounds designed to optimized with that particular water.