Fascinating facts about octopuses (not octopi)

Did you notice the word octopuses in the title and cringe at our error? Actually, octopi is not the plural of octopus as is generally thought.

The error comes from the assumption that 'octopus' is a Latin word when it is in fact Greek. The true plural would be 'octopodes' but it has been accepted that 'octopuses' is the correct plural in the English language.

The biggest giant Pacific octopus ever recorded reached a weight of 600 pounds. That’s nearly four times the weight of the average person. This huge octopus was also 30ft across – longer than a London bus.

The smallest type of octopus discovered is called an octopus wolfi, weighing only a gram and can also be found in the Pacific but in shallower waters.

Octopuses can use their tentacles to walk along the beach if they are trapped in a low tide or hunting for prey among the rock pools. After eating all the prey in one pool, they can pull themselves out of the water to go and find the next place to hunt.

If you see an octopus walking on land, make sure you give it plenty of space so you don’t frighten it. If you think something may be wrong, contact the British Divers Marine Life Rescue. Never attempt to put any marine animal back in the ocean without help or advice from the experts, as it may be sick or injured.

Watching octopuses effortlessly change colour to match their surroundings is truly mesmerising. Their ability to do this is all the more remarkable when you realise that, unlike humans, octopuses are unable to distinguish colour using their eyesight. This suggests that they are likely to be colour blind. Yet they are also some of the fastest colour-changers in the animal kingdom and can alter their appearance faster than we blink. So, how do they do it?

The secret lies in specialised cells found in their skin called ‘chromatophores’. Altering the shape and size of these colour-changing cells allows octopuses to be camouflaged from potential prey and predators. It remains a mystery how they know which colour to become so as to blend in with their environment. Some theories suggest that octopuses can see patterns of light waves, while others suggest they detect changes in brightness and contrast. Whatever the reason, this remarkable adaptation highlights their unique ability to survive and thrive in diverse marine environments.

Octopuses are clever. They can open jars (both from the inside and the outside). They can build a fortress of stones around them as they sleep to protect them from predators. And they are masters of camouflage – the mimic octopus impersonates a deadly sea snake to scare off predators and other species hide and protect themselves by carrying around a shell or coconut.

They are more than 300 different species of octopus (that we know of). Like all marine life, they are seriously threatened by pollution, loss of habitat and over-fishing. The decline of octopuses also threatens the sharks, birds, whales, dolphins and fish that eat them. The marine food web is deeply interconnected, so protecting every species counts.

If you’d like to help protect octopuses, here are some ideas:

• Use non-toxic cleaning products in your home and at work.
• Reduce your consumption of fish and only buy fish recommended in our Good Fish Guide.
• Introduce more organic food into your diet, which is not sprayed with pesticides or chemicals that run off into rivers and the sea.
• Reduce how much single-use plastic you use.
• Wash synthetic clothes in a protective washing bag to prevent microfibres ending up in the sea.
• Purchase goods in local shops to reduce the disturbing noise and carbon emissions associated with international shipping.
• Support us by donating or volunteering at a beach clean.