Does an octopus have blood? Why do octopuses have blue blood?

A LITTLE ANATOMY. BLUE BLOOD AND THREE HEARTS

Octopuses are cousins of oysters. Like all mollusks, their body is soft and boneless. But they carry the shell, or rather its underdeveloped remnant (two cartilaginous rods), not on their back, but under the skin of their back.

Octopuses are not simple mollusks, but cephalopods . On their heads grow tentacle-like arms, which are also called legs, because the animals walk on them along the bottom, as if on stilts.

Squids and cuttlefish are also cephalopods. They differ from octopuses only in appearance. Squids and cuttlefish have not eight, but ten tentacles and a body with fins (regular octopuses do not have fins). The cuttlefish's body is flat, like a flatbread; in squid it is cone-shaped, like a pin. At the narrow end of the “pin” (where the tail should be!) diamond-shaped fins stick out to the sides.

The shell of a cuttlefish is a calcareous plate, while that of a squid is a chitinous feather, similar to a Roman gladius sword. Gladius is the name given to an underdeveloped squid shell.

The tentacles of cephalopods surround the mouth like a corolla. Suckers sit on the tentacles in two rows or in one, less often in four. At the base of the tentacle the suckers are smaller, in the middle they are the largest, and at the ends they are very tiny.

The cephalopod's mouth is small, the pharynx is muscular, and in the throat there is a horny beak, black (in the squid it is brown) and curved, like a parrot's. A thin esophagus runs from the throat to the stomach. Along the way, like a dart, it pierces right through the brain. After all, octopuses have a brain - and it’s quite large: it has fourteen lobes. The octopus brain is covered with a rudimentary cortex of tiny gray cells - the control center of memory, and is also protected on top by a cartilaginous skull. Brain cells tightly fit the esophagus on all sides. Therefore, octopuses (squids and cuttlefish too), despite their very predatory appetites, cannot swallow prey larger than a forest ant.

But nature has endowed them with a grater, which they use to puree crabs and fish. The fleshy tongue of cephalopods is covered with a hemispherical horny sheath. The cover is lined with tiny teeth. The cloves grind food, turning it into pulp. Food is moistened in the mouth with saliva and enters the stomach, then into the cecum - and this is essentially the second stomach.

There is both a liver and a pancreas. The digestive juices they secrete are very active - they quickly digest food in four hours. In other cold-blooded animals, digestion takes many hours; in flounder, for example, 40-60 hours.

But here’s what’s most striking: cephalopods have not one, but three hearts: one drives blood throughout the body, and the other two push it through the gills. The main heart beats 30-36 times per minute.

They also unusual blood - blue! dark blue when oxygenated and pale in the veins.

The color of animal blood depends on the metals that make up the blood cells (erythrocytes) or substances dissolved in the plasma.

In all vertebrates, as well as in earthworms, leeches, house flies and some mollusks, iron oxide is found in a complex combination with hemoglobin in the blood. That's why their blood is red. The blood of many sea worms, instead of hemoglobin, contains a similar substance - chlorocruorin. Ferrous iron was found in its composition, and therefore the color of the blood of these worms is green.

And scorpions, spiders, crayfish and our friends - octopuses and cuttlefish have blue blood. Instead of hemoglobin it contains hemocyanin, with copper as the metal. Copper gives their blood a bluish color.

Oxygen is combined with metals, or rather with the substances in which they are included, in the lungs or gills, which is then delivered to the tissues through the blood vessels.

The blood of cephalopods is distinguished by two more striking properties: a record protein content in the animal world (up to 10%) and a salt concentration common in sea water.

The latter circumstance has great evolutionary meaning. To understand it, let’s make a small digression, between stories about octopuses, let’s get acquainted with a creature close to the ancestors of all life on Earth, and use a simpler example to trace how blood originated and what paths it took to develop.

Octopuses are amazing cephalopods, but one of their most important mysteries is blue blood. The liquid that carries oxygen to the organs of animals is usually red, it can be lighter or darker, it all depends on the amount of hemoglobin. Blue blood in the octopus and some other mollusks is an exception for terrestrial animals; only some species chose the blue pigment hemocyanin instead of the usual hemoglobin to deliver oxygen.

For a long time, the question of why some cephalopods deviated from the usual pattern of blood formation remained open. It turned out that blue blood in octopuses is a necessary factor for survival in cold waters. The temperature of Antarctic waters ranges from -2 - +2 degrees Celsius. In such cold conditions, the transport of oxygen to tissues is difficult. The copper-based protein hemocyanin is a more effective means of delivering the vital oxidant to cells than hemoglobin at temperatures close to freezing.

Although a little blue-blooded trick helps octopuses survive in cold places, warmer waters are much more favorable for them, most species are best adapted to 10 degrees Celsius. This is the temperature that is typical for the low latitudes of the Southern Ocean, but the ability to survive in less favorable conditions is a good bonus for the species.

It is impossible not to admit the fact that octopuses are amazing creatures. And this applies not only to their unusual limb structure. They are similar to humans: they can think, communicate and use improvised means if necessary (and they have eight “arms”!). We can only be amazed at this extraordinary miracle. The primary factor, the researchers say, is the presence of “blue blood.” However, why does it have such colors?

Copper pipes

“Blue Bloods” does not classify them as belonging to an old family of noble blood, and, of course, you will never see a crown on their head. In fact, their blood is blue, and the substance that is responsible for this extraordinary color allows these individuals to better adapt to the external environment.

The name of this substance is hemocyanin; it contains a protein with copper atoms, through which oxygen enters the body through the blood. Are you familiar with the color of copper sulfate? The blood of an octopus gets a similar shade, because it contains blue bodies, and not red ones as expected. By the way, humans and other mammals living on earth have the same protein with a similar role. Its name is known as hemoglobin, its basis is iron, it is this that gives the blood its red color.

This is what hemocyanin provides. Thanks to it, octopuses can survive in conditions that are lethal to many other marine inhabitants - from -2°C to the high temperatures of underwater ocean sources.

Eight-legged brain

But that's not all. An octopus is essentially one big brain that needs to be fed with oxygen. Its 500 million neurons are distributed throughout the head and body. Of course, this does not compare with the 100 billion neurons in our brain, but octopuses are not candidates for the Nobel Prize, and their intelligence is quite enough for everyday needs.

For example, in Indonesia, octopuses collect halves of coconut shells before a storm, and then use them as shelter: they climb into one half and cover themselves with the other. And Jean Boal, a behavioral researcher at Millersville University who studies the inner life of octopuses, believes that octopuses are excellent at communicating and transmitting specific signals.

When she tried to feed the test octopuses rotten squid, one of them caught her eye and pointedly shoved the squid into the garbage disposal.

Still, there is some kind of aristocracy in blue blood!

There are about 300 species of octopuses in total and they are all truly amazing creatures. They live in subtropical and tropical seas and oceans, from shallow waters to a depth of 200 m. They prefer rocky shores and are considered the most intelligent among all invertebrates. The more scientists learn about octopuses, the more they admire them.

1. An octopus's brain is donut-shaped.

2. The octopus does not have a single bone, this allows it to penetrate into a hole that is 4 times smaller than its own size.

3. Due to the large amount of copper, octopus blood is blue.

4. The tentacles contain more than 10,000 taste buds.

5. Octopuses have three hearts. One of them drives blue blood throughout the body, and the other two carry it through the gills.

6. In case of danger, octopuses, like lizards, are able to throw away their tentacles, breaking them on their own.

7. Octopuses camouflage themselves with their environment by changing their color. When calm they are brown, when frightened they turn white, and when angry they acquire a reddish tint.

8. To hide from enemies, octopuses emit a cloud of ink; it not only reduces visibility, but also masks odors.

9. Octopuses breathe through gills, but can also spend quite a long time out of water.

10. Octopuses have rectangular pupils.

11. Octopuses always keep their home clean; they “sweep” it with a stream of water from their funnel, and put the remaining food in a specially designated place nearby.

12. Octopuses are intelligent invertebrates that can be trained, remember their owners, recognize shapes and have an amazing ability to unscrew jars.

13. Speaking about the unsurpassed intelligence of octopuses, we can recall the world-famous octopus-oracle Paul, who guessed the outcome of matches involving the German football team. Actually, he lived in the Oberhausen Aquarium. Paul died, as oceanologists suggest, of natural causes. There was even a monument erected to him at the entrance to the aquarium.

14. The personal life of sea creatures is not very happy. Males often become victims of females, and they, in turn, rarely survive after childbirth and doom their offspring to an orphaned life.

15. There is only one species of octopus - the Pacific striped one, which, unlike its fellows, is an exemplary family man. He lives in a couple for several months and throughout this time he performs something very similar to a kiss, touching his mouth with his other half. After the birth of the offspring, the mother spends more than one month with the children, taking care of them and raising them.

16. This same Pacific striped fish boasts an unusual hunting style. Before the attack, he lightly pats his victim “on the shoulder,” as if warning, but this does not increase his chances of survival, so the purpose of the habit still remains a mystery.

17. During reproduction, males use their tentacles to remove spermatophores “from behind the sinus” and carefully place them in the mantle cavity of the female.

18. On average, octopuses live 1-2 years; those who live up to 4 years are long-livers.

19. The smallest octopuses grow up to only 1 centimeter, and the largest up to 4 meters. The largest octopus was caught off the coast of the United States in 1945, its weight was 180 kg and its length was as much as 8 meters.

20. Scientists managed to decipher the octopus genome. In the future, this will help establish how they managed to evolve into such an intelligent creature and understand the origin of amazing cognitive abilities. It is currently known that the length of the octopus genome is 2.7 billion base pairs, which is almost equal to the length of the human genome, which has 3 billion base pairs.

Octopuses are amazingly complex creatures. And it’s not just the unusual structure of their limbs. They know how to think ahead, communicate and use improvised means when needed (fortunately, they have eight “hands”). One is left wondering how they manage to do this. Scientists say the main reason is “blue blood”. But why is it this particular color?

Copper pipes

No, octopuses do not belong to an ancient noble family, there are no august persons among them, and they do not wear a crown on their heads. The fact is that they actually have blue blood, and the substance that is responsible for such an unusual color allows these creatures to better adapt to their environment.

This substance is called hemocyanin and is a protein with copper atoms, which carries oxygen throughout the body through the blood. Remember the color of copper sulfate? The blood of octopuses takes on the same hue: because it contains blue blood cells rather than red ones. By the way, humans and other land mammals also have a protein with similar functions. It is called hemoglobin, instead of copper it is rich in iron and gives the blood its red color.

But why does an octopus need blood with hemocyanin? The fact is that these creatures live on the seabed, where there is very little oxygen, and do not live long, so even over millions of years of evolution they could not migrate to more favorable conditions. That's why octopuses have three hearts that constantly pump oxygen-rich blood into their bodies. This is what hemocyanin provides. Thanks to it, octopuses can survive in conditions that are lethal to many other marine inhabitants - from -2°C to the high temperatures of underwater ocean sources.

Eight-legged brain

Still, there is some kind of aristocracy in blue blood!