Swimming with cockatoos?

As part of our exhibition we want to ‘bring the squid to life’. So we’re developing an animation to give you an idea of how the squid lives and how it swims.  Only problem is– nobody has ever seen a live colossal squid swimming, so nobody knew what it would look like!

So it was over to the Te Papa scientists to come up with a hypothesis of how the squid swims and to explain it to the animators and designers.

Cranchiids or glass squids

The scientists looked at how other closely related squids swim. There are many videos of other squid species swimming, including the family Cranchiidae or glass squids, to which the colossal squid belongs. 

Cranchiids or glass squids have a very different morphology or outward appearance to most squid. With their binocular vision and forward directed eyes they cannot hold their arms out directly in front as in most squid.

Cockatoo position or not?

Cranchiids therefore hold their arms either up over their heads (“cockatoo” position) or downwards (“reverse cockatoo” position). You can see this in an underwater video from the NOAA Oceanexplorer website.

http://oceanexplorer.noaa.gov/explorations/04etta/logs/aug26/media/bathyscaphoid_squid_video.html

There is an on-going debate around whether the colossal squid swims in the “cockatoo” position or “reverse cockatoo”.  Because of the differences in body morphology between Cranchiids and other squids, we know that the colossal squid does not swim with its arms held flat (unless it is about to attack a prey item).

Most other squids have the eyes placed on the sides of the head – this means that they do not have to lift their arms out of their field of vision and can swim with the arms flat. You can see this in the following video:

By carefully measuring the length of the arms the scientists were able to determine how the arms would be held if all the tips were together.                                   

Measuring the colossal squid.   Image Copyright Te Papa

Measuring the colossal squid. Image Copyright Te Papa

For example if the arms are held upwards, then the lower arms would be longer as they would have to reach further to meet the tips of the upper arms, as well as examining the positioning and direction of the non-swivelling hooks, it was possible to come up with a hypothesis that the “cockatoo” position was used by our specimen. 

As no one has ever seen a Colossal Squid actually swimming, all we can do is put forward a hypothesis, aka educated guess, based on what we know about other types of squid.

This is the process of science!

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