Fun with cups

Yesterday we were having fun with cups. Not normal cups, but polystyrene cups – they’re made of thick squishy plastic, squishy because they are full of air bubbles (bubbles too small to see). The air bubbles help keep the heat in the cup so that your hands don’t get too hot – Meg and Woody like hot chocolate in their polystyrene cups. 

What does this have to do with exploring the sea?  Yesterday we reached the deepest point of our journey – it was 2800m deep (280 double decker buses back to back - VERY deep). Deep, very dark, and very cold. We wanted to know how cold, how salty and how much oxygen is down there (that’s in the air we breathe and needed for nearly all life on this planet). To do this we lower a big machine that measures the temperature (how warm or cold the water is), salinity (how salty it is), and how much oxygen there is, on a LONG cable all the way to the bottom of the sea and back. Here are Meg and Woody with the machine (actually called a CTD rosette), and being lowered in the sea:

It measures the temperature, saltiness and oxygen all the way from the surface to the bottom – it starts of quite warm (the temperature of the sea in winter, around 11°C – tried dipping your toe in the sea in February?) and gets very cold at the bottom (2°C, you wouldn’t want to jump in water at this temperature even with a wetsuit on, nearly cold enough to turn into ice).

So at this deepest part of our survey, we attached polystyrene cups to the CTD machine and sent them to the bottom of the sea and back. This is a Meg & Woody with the cups designed by Daisy & Pippa, before and after they went to the bottom of the sea (2800m):

They came back really tiny! Why? Water is heavy. Hold a big bucket of water and try carrying it around. Heavy isn’t it? Well imagine 2800m of water on top of you (280 double decker buses full of water). It would squash you! And that’s what has happened to the cups, the water pressure (the weight of the water on the cup) has squeezed all the air out of the cups to make them the tiny size Meg & Woody are now holding. What is amazing is that animals like sperm whales are able to dive to the bottom of the sea without getting squashed (wow!). And there are animals that live all their lives at the bottom of the sea. Science is pretty amazing! And the cups are now a perfect size for Meg and Woody for their hot chocolate :)