Glass octopus in the Atlantic Ocean off Cabo Verde

© Solvin Zankl/Minden Picture

See-through cephalopod. World Octopus Day

This glass octopus, part of the Octopoda order, is among the most mysterious marine animals. It resides at a depth of around 3,000 feet in the ocean, where sunlight cannot penetrate so they are seldom seen and hard to observe. Octopuses (sometimes pluralised as octopi or even octopodes) become more intriguing as we gain more knowledge about them. These marine animals are known for being behaviorally diverse and intelligent, able to remember and recognise humans and use tools.