1. Octopuses have been around for a long time: The oldest known fossil of an octopus ancestor belongs to an animal that lived around 330 million years ago, long before the dinosaurs. Discovered in Montana’s Bear Gulch limestone formation and described in 2022, the specimen had ten limbs, while modern octopuses have just eight. Long before life on land evolved, octopuses had already established their form millions of years later. Photo:BBC

2. Octopuses have three hearts: Two of these hearts function solely to send blood through the gills, where it releases carbon dioxide and absorbs oxygen. The third heart then circulates that oxygen-rich blood to the organs and muscles, providing them with energy. But the second heart actually stops beating when the octopus swims, which exhausts them, which is why they prefer to crawl instead of swim. Photo:Quora

3. Octopuses aren’t stupid: They have big brains for their size, and they can figure out how to open a seashell that’s been sealed shut with string, for example. They can navigate mazes, solve problems, memorize solutions, and take things apart for fun. Octopuses even have distinct personalities. Finally, cephalopods can play a game of catch with a floating bottle. Photo: Exhibit Galleries Blog

4. Octopus arms have a mind of their own: Two-thirds of an octopus’s neurons are in its arms, not its head. As a result, some arms can figure out how to open a clam while the rest of the animal is busy doing something else, like checking out a cave for more tasty treats. Octopus tentacles can even react after they’ve been completely severed from a dead animal. In one experiment, amputated tentacles twitched and curled when researchers pinched them. Photo: Lab Manager

5. Octopus ink doesn’t just help hide: Squid also physically harms predators. It contains a compound called tyrosinase, which in humans helps control the production of the natural pigment melanin. But when sprayed into a predator’s eyes, tyrosinase causes irritation. It also disrupts the creatures’ sense of smell and taste. Photo: Smithsonian Magazine

6. Octopuses have blue blood: Living in the deep ocean, octopuses’ blood is fueled by a copper-containing protein called hemocyanin. While our iron-rich blood turns red when exposed to oxygen, the copper in octopus blood turns it blue. Hemocyanin, a larger protein, transports oxygen more efficiently in the harsh environment in which octopuses live: At the bottom of the ocean, water temperatures are very low and there isn’t much oxygen around. Photo: Goodreads

Octopuses’ blood also makes them extremely sensitive to changes in acidity. If the pH of the surrounding water is too low, the animals can’t circulate enough oxygen to survive. As a result, researchers are worried about what will happen to octopuses as climate change increases ocean acidity. Photo: ScienceABC

7. After mating, life is over: Mating and parenthood are short-lived affairs for octopuses, which die shortly afterward. The species practices external fertilization. A male deposits his sperm directly into the female’s mantle cavity, using his hectocotylus, a special, longer arm. The male’s “genital arm” then falls off and the animal dies. Photo: Science Times

As for females, they can lay up to 400,000 eggs. To prioritize motherhood, they stop eating. When the eggs hatch, the female octopus dies. Her optic glands rapidly produce self-destructive chemicals, causing a rapid change in cholesterol metabolism that eventually kills her. Some captive octopus mothers have been known to deliberately hasten their own deaths by self-mutilation. Photo: BGR

8. Most of the octopus we eat comes from North and West Africa: Octopus meat has been a popular food in East Asia, Spain, Greece and other countries for centuries, and recently, demand for it has expanded to the United States and elsewhere. Photo:Taste

But its culinary popularity has had an impact on octopus populations around the world. Global production of octopus now exceeds 550,000 tonnes per year. Photo: My Greek Dish