Northwest Fisheries Science Center

Newportal Blog

A gateway to oceanographic adventures from the Newport Line and beyond

Blog on ocean conditions along the Newport Line and the northern CA Current.

Under pressure!

By Jason Phillips
March 1, 2017

At-sea research trips have some down time. In the distant past, a bored scientist with a sense of humor drew a picture with a Sharpie on a piece of Styrofoam and sent it way down into the abyss, securely attached to a piece of equipment. When he or she brought it back up, the object was shrunken to a tiny size. The reaction was joy among fellow scientists-- and a tradition was born.

Styrofoam cups prepared for their trip to 1,000 meters.

My main job this trip is to run the beam trawls (a small bottom net) with video equipment when we are near shore to collect juvenile commercial flatfish.  However, we spend some time offshore (out to 200 miles) collecting samples. While away from the coast, I don’t have much to do. I brought data to enter, but I can’t exactly head home after a day’s work.  Fortunately, one thing that we do offshore is collect data on the water column by sending a CTD down to 1,000 meters.

I took this opportunity to teach some elementary students a little physics to spark their interest in science.  This trip, we will crush some cups for science. 

Before I departed on the research cruise, I sent 40 Styrofoam cups to kids in a 5th grade class with instructions to decorate them with colored Sharpies. Some kids are great artists, surpassing my own stick figure cup-coloring abilities.  I have sent the cups down in 2 batches and plan to return them to the artists once I reach dry land, where I’ll explain the process.

How does this cup crushing thing work?

The cups secured to the CTD rosette.

At sea level, the air that surrounds us presses on our bodies at 14.5 pounds per square inch.  We don’t notice it because we are adapted to it, but it is happening… If that pressure was removed you would definitely notice as your blood would literally boil as many other bad things happen. The opposite is true as you go underwater.  Dive down to the bottom of a swimming pool and you can feel increased pressure in your eardrums. This is due to an increase in hydrostatic pressure, the force per unit area exerted by a liquid on an object. The deeper you go, the greater the pressure of the water pushing down on you. For every 33 feet (about 10 meters) that you go down, the pressure increases by 1 atmosphere.

Styrofoam cups are mostly air, about 90%. When sent down to great depths in the ocean, pressure builds up all around them forcing the air out of the cup and causing it to shrink. We are sending these cups down 2,000 meters. This will result in an added 200 atmospheres of pressure or 2,900 pounds per square inch (PSI). 2,900 PSI would be like crushing a car down to a 1 inch cube. Imagine a bunch of cars getting crushed to 1” and being placed all around you. Without some very strong protection, say a submarine, a human would not be able to survive. However, many animals that live in the sea have no trouble at all with high pressure. For example sperm whales can hunt for giant squid at depths over 7,000 feet. 

I could go on, but the CTD is coming back up and I need to go…

The tiny styrofoam cups after a trip to 1,000 meters.

Tagged: NCC

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