Michael Pitts / Blue-ringed octopus (Hapalochlaena) Sulu Sea, Philippines.

Alex Mustard / Blue ringed octopus (Hapalochlaena lunulata) swims, jet propelled, across coral. Dampier Strait, Tropical West Pacific Ocean.

Alex Mustard / Tropical blue ring octopus (Hapalochlaena lunulata) is small but has one of the most venomous creatures in the ocean, its bite injects a neurotoxin that paralyses its victim. It flashes its blue rings...

Alex Mustard / A blue ring octopus (Hapalochlaena lunulata) flashes its blue rings as it crawls over a coral reef. Kapalai Island, Sulu Sea, Sabah, Borneo, Malaysia..

Alex Mustard / Tropical blue ringed octopus (Hapalochlaena lunulata) free swims just above the seabed. Lembeh Strait, Molucca Sea Sulawesi, Indonesia

Alex Mustard / An undescribed species of blue ring octopus (Hapalochlaena sp.) swimming at night. Java Sea, Puri Jati, Bali, Indonesia. South East Asia.

Jeff Rotman / Scientist holding a poisonous Pacific blue-ringed octopus (Hapalochlaena maculosa) in his hand. The octopus can emmit a fatal neurotoxin through it's saliva when provoked, and there is no known anti-v...

Juergen Freund / Blue-ringed octopus (Hapalochlaena lunulata) moving over seabed, Batangas, Philippines.

Juergen Freund / Blue-ringed octopus (Hapalochlaena lunulata) swimming through water, Batangas, Philippines.

Juergen Freund / Blue-ringed octopus (Hapalochlaena lunulata) swimming through water, Batangas, Philippines.

Juergen Freund / Tropical blue-ringed octopus (Hapalochlaena lunulata) hunting. Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Tropical blue-ringed octopus (Hapalochlaena lunulata) hunting on the coral. Lembeh Strait, North Sulawesi, Indonesia.