Giant squid (Architeuthis sp.). This sea creature has been the focus of myths and legends for more than two thousand years. Although this cephalopd mollusc does exist, what little is known about it has come from dead specimens that have washed up on shore or captured in nets by fishermen. The giant squid is the largest invertebrate animal in the world and amongst the most complex. It is a deep-ocean dweller, living at depths of 300-600 metres. It is thought to grow to between 17 and 20 metres. An adult has never been seen alive, although it may be possible to capture juveniles and maintain them in an aquarium in order to learn more about this creature's biology and habits.