The octopus is thought to have been around for hundreds of millions of years, and over that time, scientists have carried out extensive research on everything from their habitats to their anatomy. Here, we’re delving into the main features of the common octopus and how these adaptations and developments help them move, eat and survive.
What is an octopus?
Famously clever problem-solvers, octopuses are fascinating marine creatures. The common octopus (Octopus vulgaris) is a type of mollusc, belonging to the class Cephalopoda. One of many fascinating facts worth knowing about them is that they are considered the most intelligent invertebrates in the world.
There are many species of octopus in our oceans, including the giant Pacific octopus, which can grow up to 16 feet long!
Anatomy of an octopus explained
Octopuses have a distinctive appearance and several key anatomical features that set them apart from other creatures in the marine world, so let’s explore these in more detail!
Brain
Famed for their extreme intelligence, you might be wondering where all their cleverness comes from. The answer is that octopuses have a total of 9 brains.
The first is the central brain, which is essentially the boss of all the other brains. It controls complex decision-making, learning and memory, alongside being able to send signals to the other 8 brains.
They then have 8 ganglion brains at the base of each arm. It’s thanks to these brains that octopuses can move each arm independently, allowing them to open jars, build dens and hide in small spaces.
Arms and suckers
While you might be tempted to call them tentacles, octopuses actually have arms – 8 of them to be exact. Each of these is powerful and flexible, helping these creatures move around easily.
On each arm, you’ll find rows of suckers or suction cups. These contain sensory nerves for taste and touch, which allow them to taste, move objects and detect prey, all with just their arms.
Ink sac
Found near the gut, the ink sac stores melanin-rich dark ink. This ink will be released by an octopus when it feels threatened by predators or is trying to disorient its prey, acting as an excellent defence mechanism.
Eyes
Octopuses generally have one pair of eyes. These are thought to be more sophisticated than human eyes in many ways, especially since they can adjust their view like a camera lens. This means they have panoramic vision, helping them spot prey and predators easily. However, it’s thought that many octopuses are colour blind.
Beak
Like many bird species, common octopuses have strong beaks rather than mouths. These bone-like structures are made of chitin, which is also found in insect exoskeletons and fungal cell walls. The beaks have a stiffness gradient; the tip is hard, but the base is soft and flexible. This is so it doesn’t damage the octopus where the beak meets the tissue. An example is the Humboldt squid, who’s beak is harder than nylon and close to the hardness of metal dental fillings!
Heart
Keeping up with the theme of having multiples of everything, octopuses have 3 hearts. Two of these are in charge of controlling blood flow to the gills, helping the octopus breathe underwater. Meanwhile, the other heart circulates oxygenated blood around the body for all vital organs.
Anatomy poster of an octopus
Click on the arrows in our interactive poster below to discover the different features of the common octopus and what they do.
Additional must-know facts about octopuses
Ready for some more exciting octopus-related facts? Let’s dive straight in:
- They’re blue-blooded: These clever creatures have developed a copper-based bloodstream, which allows the blood to flow easily between their 3 hearts and 9 brains.
- They don’t have bones: Instead, octopuses have what’s known as a hydroskeleton, which means they have a fluid-filled muscle system. This helps them with flexibility and squeezing into small crevices underwater.
- They’re masters of camouflage: Thanks to a chemical under their skin called chromatophores, octopuses can change their colour and texture to blend into their surroundings and protect themselves.
- They can regenerate limbs: Like starfish, octopuses can regenerate entire limbs within just weeks or months because of special cells called blastema.
Spot the common octopus at Bristol Aquarium
Here at Bristol Aquarium, we have our very own common octopus in our Ocean Floor exhibit. You can learn plenty more interesting facts and see their fascinating features up close at one of our Talk and Feed sessions, running daily.
Book your tickets today to visit our common octopus and many more exciting marine creatures!