Tuesday, 6 September 2011

"The Inspector Gadget of the Oceans".

Meet the "Inspector Gadget of the Oceans" otherwise known as the Little Leonardo W2000-3MPD3GT data logger, a very important tool in our trade and one that is helping us to shed light on many new and interesting aspects of whale behaviour. 

The Inspector Gadget of the Oceans (W2000-3MPD3GT) ready to go in his white floatation suit and piggy backing a Sirtrack GPS data loger. The Rising Sun on the tail is in honour of our Japanese friends and collaborators at the University of Tokyo.

Like "Inspector Gadget", the W2000-3MPD3GT has many tricks hidden within it's tiny body. The data logger is about the size of a small hand held torch (ΓΈ28 x 168 mm ), weighs 168g and has 512mb of memory; but for it's size it packs a mighty punch, and is able to record nine different parameters during it's ride on a whale's back.
  1. 3M or Three Axis Magnetometer. The tree axis magnetometer records the strength of the earth's magnetic field every second in three different planes; X, Y and Z. This data is used to give us the whales heading with respect to magnetic north.
  2. P or propeller. The propeller at the front of the logger logs the whale's speed through the water every second.
  3. D or depth. A pressure sensor in the Logger records the whale's depth every second, enabling us to see where in the water column it is diving.  
  4. 3G or Three axis accelerometers. Inspector Gadget's 3 axis accelerometers measure the acceleration due to gravity every 1/3rd of a second in three different planes; X, Y and Z. We use the data from the accelerometers to measure how well an individual whale glides through the water, and how often it has to stroke (beat it's flukes) allowing us to assess it's overall body condition.
  5. T or temperature. A small temperature sensor at the back of the data logger measures the water temperature through the water column as the whale dives. Water temperature affects both the speed of sound, very important for species that have evolved to use sound for communication, and the structure of the water column.

Our Inspector Gadget wears a sleek, white, torpedo shaped floatation suit, and is attached to the whale using a suction cup. His floatation suit also houses a VHF radio beacon and a timer release mechanism.  The VHF beacon allows us to track the whale each time it surfaces to breathe, and also allows us to find our Inspector Gadget again once he releases from the whale. The timer release mechanism is used to break the vacuum in the suction cup so that our Inspector Gadget can return to the surface with his valuable data.

The Inspector Gadget of the Oceans hitches a ride on "Splish" (H002).

When we get back to shore we give Inspector Gadget a good bath in fresh water, dry him down and then plug him into my laptop to download his memory.  It is only now that we get a first look at the raw data he has recorded.

Raw data captured by Inspector Gadget during his five hour and forty minute ride on "Splish" (H002).

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