As a fan of pointless comparisons, I rather enjoyed this one in which a double-decker bus is used as the standard measure. (Other standard measures are VW Beetles for meteorites and the MCG for areas of deforestation. Fossil horses have been measured in fox terriers and German shepherds. And we all know how many holes it takes to fill the Albert Hall.)
In 2003, the giant squid (Architeuthis) rocked in at a respectable 18 m. That's equivalent to 2.25 double-decker buses. It was a beast worthy of the epithet 'giant'. Two and a quarter double-deckers-worth of writhing tentacles and murderous beak would surely cause any ship's timbers to shiver. 
But today's Architeuthis has wasted away to nothing. A wisp, barely 1.625 buses long. How could something of those meagre dimensions strike terror into the hearts of sailors becalmed in the Sargasso Sea? Or wherever. Avast, me hearties! There be a moderate-sized squid. Arrr!
The colossal squid is clearly winning the cephalopod PR war.
