Most living things have red blood and only one heart in their bodies. But deep in the ocean lives a creature whose blood is blue instead of red and who has three hearts. It has nine brains, which is even more interesting. The octopus is an incredibly unique marine animal. Today, we'll look at 11 amazing things about this amazing animal.

1. They have three hearts and blue blood.

Let's talk about their biology first. Octopuses have three hearts, not just one like we do. Two branchial hearts pump blood to their gills, where it gets oxygen. The third, bigger systemic heart then sends this oxygen-rich blood to the rest of their body. That's not all, though. Their blood isn't red like ours. It's a shade of blue. This is because octopuses and other cephalopods use hemocyanin, a copper-rich protein, to carry oxygen instead of hemoglobin, which is made of iron. Hemocyanin is better at moving oxygen in cold, low-oxygen places, which makes it perfect for living in the deep sea.

2. They are very smart and good at solving problems.

Many people think that octopuses are some of the smartest invertebrates on Earth. They have a complicated nervous system and a brain-to-body size ratio that is pretty big. People say they are great at solving problems. People have seen them open jars with child-proof lids, find their way through complicated mazes, and even take lightbulbs out of their sockets! There is also a lot of evidence that they are curious because they like to explore and play with new things in their environment.

3. Each of their arms has its own "brain."

Octopuses do have a brain in the middle of their bodies, but two-thirds of their neurons are in their arms. This means that each arm can think and do things on its own, which makes it possible to coordinate and do many things at once.An arm can feel around in a crevice, taste the things around it, and even respond to things without the central brain telling it to. This unique decentralized nervous system is one of the things that makes them act in such complicated ways.

4. They are experts at hiding.

Do you think chameleons are good at hiding? Octopuses are better than them. Chromatophores, leucophores, and iridophores are special skin cells that allow octopuses to change the color, pattern, and texture of their skin in the blink of an eye so they can blend in with their surroundings. They don't just passively react; they actively choose how to look to hide from predators or surprise prey. Some species can even look like other animals, like lionfish or poisonous sea snakes.

5. Their "ink" is a complicated way to protect themselves.

When an octopus feels threatened, it can release a dark ink cloud made mostly of melanin, the same pigment that gives our skin and hair their color. This cloud of ink hides the octopus's escape by acting like smoke. But it's not just a way to scare people off. The ink also has chemicals that can make predators' eyes hurt and mess up their sense of smell, giving the octopus a few extra seconds to get away.

6. They live alone.

Octopuses don't like to be around other animals very much. They make their homes in rock crevices, coral reefs, or even old shells that they find. They are very territorial and usually only come together to mate. After mating, the males usually die soon after, but the females spend the rest of their short lives guarding their eggs.

7. Their lives are very short.

Octopuses are very smart, but they only live for a very short time. Most kinds only live for one to five years. This is part of a "live fast, die young" plan, where they grow quickly, have a spectacular reproduction, and then die of programmed aging. It's a sad contrast to how smart and capable of learning they seem to be.

8. They Can Grow Back Lost Arms

An octopus doesn't die if it loses an arm. They can grow back whole limbs, with nerves and suckers, in just a few months because they can heal themselves so well. Although this process requires a lot of resources and is complicated, it is an essential survival adaptation in the harsh marine environment.

9. Some octopuses construct and embellish their dens

Some octopuses exhibit signs of creativity and foresight in addition to intelligence. In order to construct safe havens, species such as the veined octopus have been seen gathering coconut shells and transporting them over great distances. In a manner akin to underwater landscaping, they carefully place the shells around their dens. This behavior exhibits advanced tool-use and planning skills.

10. Their Suckers Are Independent

An octopus has hundreds of suckers, each of which can be controlled separately. They have enormous power and can produce a lot of suction force. However, they also function as chemoreceptors and tactile organs, making them exceptionally sensitive. An octopus can thus "taste" objects simply by touching them with its suckers, giving it a wealth of information about its environment and possible prey.

11. They are Prehistoric Animals

Although octopuses are short-lived individuals, the cephalopod lineage is very old. The octopuses themselves predate many kinds of dinosaurs by hundreds of millions of years. Their distinctive adaptations and intelligence appear to have been refined over long periods of evolutionary time, based on their ancient history.

The octopus is proof of the incredible diversity and inventiveness of life on Earth. Its strange biology, sophisticated intelligence, and fascinating behaviors serve as a reminder that there is still a great deal to learn about the vast, enigmatic ocean depths. The next time you see an octopus, whether it's in a documentary or, if you're extremely fortunate, in its natural habitat, pause to appreciate this incredibly amazing and strange animal.