The Blue-Ringed Octopus
The blue-ringed octopuses are currently recognized as one of the world’s most venomous marine animals. Despite their small size and relatively docile nature, they can prove a danger to humans.
They can be recognized by their characteristic blue and black rings and yellowish skin. When the octopus is agitated, the brown patches darken dramatically, and iridescent blue rings or clumps of rings appear and pulsate within the maculae. Typically 50-60 blue rings cover the dorsal and lateral surfaces of the mantle. They hunt small crabs, hermit crabs, and shrimp, and may bite attackers, including humans, if provoked.
Definition from wikipedia.org
Photos by divers.ph