Do we have octopus and are they dangerous?

April 2004

Yes, we have octopus. Our species, Octopus vulgaris, isn’t dangerous, and most octopus are completely harmless, excluding the small, blue-ring octopus of Australia that can inject a dangerous and sometimes deadly neurotoxin.

Octopus can be hard to find because of their superior skill at camouflage.

Octopus vulgaris is found worldwide in tropical and semitropical waters and can live in nearshore waters or as deep as 600 feet. Like most of the world’s 200 octopus species, it is secretive and needs reef and rocky bottoms for hiding. Although our sandy ocean bottom doesn’t always fit the bill, hardbottom ledges and shipwrecks just off our coast provide suitable habitat.

Octopus vulgaris has a short life span, only 12 to 18 months. The female lays eggs in long, string-like clusters, attaching them beneath a rock or other hard object. She stops eating and guards the eggs until they hatch, after which she dies. After hatching, hundreds of young octopus spend between 45 to 60 days bobbing around in the ocean’s plankton-rich waters before settling down to a bottom-dwelling existence.

Octopus are credited with amazing intelligence, and their well-developed central nervous system has been well documented. Their vision is excellent and they exhibit complex behaviors. They are masters at coordinating their eight independently working arms, also called tentacles. Each arm is equipped with numerous suckers that feel, grip and taste. This requires substantial brain power. They quickly learn to navigate mazes, distinguish colors and shapes and even unscrew jar lids to get at food inside. Their diet consists mainly of crabs, shrimp, lobsters and other crustaceans.

Octopus can change color in an instant, sometimes flashing from light to dark to brown to white to red to purple. They use this color-changing ability primarily for camouflage, however, some studies suggest it indicates mood – fear, mating, threats, territory, etc. Their rapid color-changing ability is unsurpassed in the animal kingdom and demands considerable neural coordination. They can also emit a cloud of black ink, hoping to confuse their predator, and can swim amazingly fast when threatened. The major predator of our Atlantic species is moray eels.

Octopus vulgaris may weigh up to 50 pounds and attain a 10-foot arm span, although the average is more like a few pounds and a 3-foot arm span. They are shy, quiet and retiring, and their favorite food is crabs.