‘Octopus’ in Portuguese is ‘polvo’, and Polvo à lagareiro is a quintessentially Portuguese seafood dish featuring boiled and baked octopus with mashed potatoes in a herbed garlic oil. I see it on menus all the time, so it obviously tastes good!

However, reading up on the life of an octopus reveals some unusual facts. I knew they had eight ‘arms’ and had a beak, and were quite intelligent. Most famously, they can blast a cloud of ink to throw off predators and can change their skin colour at will. But there is so much more.

There are some 300 species of octopus, a soft-bodied mollusc of the order Octopoda, grouped with squids, cuttlefish, and nautiloids. With good eyesight and a beaked mouth at the centre, their soft body can radically alter shape, enabling them to squeeze through small gaps, with eight appendages they trail behind them as they swim. A siphon is used both for respiration and for locomotion, by expelling a jet of water. They apparently don’t know what the limbs are doing unless they can see them – it’s a wonder they don’t trip over themselves and end in a tangle of sticky tentacles, but somehow they don’t. They have a complex nervous system and are among the most intelligent of all invertebrates.

They have three hearts - two pump blood to the gills and a larger main heart that circulates blood to the rest of the body. Technically, they also have nine brains because, in addition to the central brain, each of eight limbs has a mini-brain that allows it to act independently. This adds up to a lot of distributed brainpower. Since each limb has a mini-brain, the central brain just sends a higher-level signal to the limb; for example: ‘navigate to rock for possible crab below’ - in humans, our brain would guide and control each movement of our arm. With an octopus, the limb acts almost independently as it proceeds to probe round the rock, tasting and feeling with its suckers. Multiply this by eight limbs and we can see that the mini-brains take a big load off the central brain. Each limb is controlled by an elaborate nervous system consisting of more than 40 million neurons connected to the octopus’s suckers.

Blue blood

I thought Royal Families were the ones reputedly to have blue blood, but the octopus really does! This is because they have adapted to cold, low oxygen water by using something called hemocyanin, a copper rich protein. And if they lose one of their limbs, like starfish, they can regenerate it, so it would be rare to find one without all arms intact.

Mating has some weird rituals for some species too, and it can be a dangerous game for the male. He reaches over with his specialised ‘arm’ (males have a modified third right arm called a hectocotylus) and delicately deposits one or two packets of sperm underneath the female’s mantle. He needs a long arm for this special delivery because she might also might fancy him for a meal, so he makes his ‘gift’ and backs off quickly, as she can turn cannibalistic as soon as she receives his love-packet.

He then goes into decline and dies, and around seven months later she will give birth to literally thousands of eggs. She doesn’t feed herself during this time and loses up to 50% of her body weight, and after they hatch, in most cases, it’s game over for her too, as she also dies. Not what you would call a healthy sex life!

Most species grow quickly, mature early, and are short-lived. They only mate once then die, with a life span of perhaps a few months, with the larger species living to maybe 3 years.

And yes, they are smart. Able to figure their way out of complex mazes, solve problems and remember solutions. Octopus intelligence is well documented - they have been known to open jars and demonstrate personalities. They seem like intelligent aliens, and maybe the closest we’ll get to meeting one - with their ovoid, head-like mantles, and eyes that seem to scan you, octopuses certainly look the part.


Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man. 

Marilyn Sheridan