Cockatoo squids cast no shadow
“They have opaque eyes that can give away their presence as they swim”
These incredible creatures are almost completely transparent, but they have opaque eyes that can give away their presence as they swim through the ocean. To prevent any shadows revealing them to predators passing below, the squids cast a bioluminescent blue glow from U-shaped cells beneath their eyes. This eliminates the silhouettes created by their eyes and makes it much more difficult for a predator to detect their exact position.

The bigfin reef squid has special light-bending cells
The bigfin reef squid is covered in special cells to make them stand out. Their heads and bodies are covered in chromatophores, which are light-reflecting cells giving them a metallic iridescent sheen. They are also one of the only squid species to possess leucophores, which are the cells responsible for reflecting the colour of the ambient light surrounding the squid. These two types of cells work in unison meaning the squid is able to produce a variety of vivid colour combinations and visually striking patterns.