(ORDO NEWS) — Imagine that you plunged into the sea off the coast of the Indonesian island of Lembek. It is shallow here – about five meters, and everything is flooded with sunlight. The water is very warm – as expected in a tropical paradise. The bottom is covered with wavy fine dark gray sand with greenish spots of silt. Looking around, you notice a lonely bivalve, quite massive. Six sharp spikes protrude from it: perhaps the host of the shell is hiding inside. Or maybe he died a long time ago, and now a hermit crab has settled in the bivalve. Out of curiosity, you decide to turn the sink over … But instead of snail horns or stalked eyes of cancer, you have large, almost human eyes, surrounded by a corolla of tentacles with suckers.
Here is an octopus, namely a coconut octopus (Amphioctopus marginatus), so nicknamed for loyalty to a coconut shell – it is in it that he prefers to hide. Sometimes this mollusk even travels with its shelter – because it may well be useful in case of danger. However, if an empty sink comes in, it will take it.
Secured by suction cups, the octopus gently holds the wings. You continue to observe and notice that, by slightly loosening the grip, he pulls himself up and leans out: assesses the situation. Frozen, so as not to frighten away the mollusk the size of a thumb, you see how he, making sure that there is no danger, leaves the sink. Moving along the sand, the octopus becomes as dark gray as the ground. Has he decided to leave? Not at all: crawling along the sand, the mollusk climbs onto the sink. Then, with a deft movement, flips it over and crawls in again.
You already decided to sail, when suddenly a barely noticeable movement catches your eye: the octopus streams the sand under the sink with trickles of water until a gap forms there. And now our hero is already peeping out from under the shell. You lean closer and your eyes intersect. He carefully looks into your eyes, as if studying. Yes, among the invertebrates of octopuses, perhaps the most human. Even among vertebrates, such an intelligent looking gaze is not common: try to imagine some fish trying to look into your soul!
Octopuses also remind people of being famous for their agility – using tentacles strewn with hundreds of suction cups, they can manipulate objects no worse than we can with our fingers, easily open the bivalve shells, screw covers from cans and even disassemble the water filtration system in aquariums. This compares them favorably with marine mammals, because the same dolphins, although smart, are very limited by the anatomy of the body – with all the desire and ingenuity, the jar cannot be opened to them.
At the same time, it is difficult to imagine creatures more unlike us: did you know that an octopus has three hearts and blue blood? And about the fact that they don’t have a skeleton? The beak, like parrots, and the dense cartilage that protects the brain – these are all the solid parts of the body. Therefore, they easily penetrate through the cracks and can escape from almost anywhere. And each suction cup is capable of moving independently of the others and is covered with taste buds – as if the human body were studded with hundreds of tiny tongues. And a lot of photosensitive cells are concentrated in the mollusk skin. But this is not the most alien quality of cephalopods. Before we reveal all the cards, let’s get to know the representatives of this tribe closer.
If people belong to the class of mammals, then octopuses are included in the class of cephalopods (Cephalopoda). The name of the class reflects the essence of their anatomy in the best way possible: the “legs”, that is, the tentacles, are located on one side of the big head, grow out of it, and the short sack-like body is on the other. The class of cephalopods belongs to the type of mollusks, which also includes gastropods (snails and slugs), bivalves (mussels and oysters), multifold chitons, and several lesser-known classes. Their story spans half a billion years and begins with a tiny creature with a sink that looks like a cap. After 50 million years, these mollusks already dominated the ocean, turning into the largest predators. Some individuals reached enormous sizes – for example, the length of the shells of the giant endocera (Endoceras giganteum) exceeded five meters.
Now the planet is inhabited by more than 750 species of cephalopods known to science. In addition to 300 species of octopus, this class includes squid and cuttlefish (with 10 tentacles each), as well as several species of nautiluses – unusual mollusks with nine dozen tentacles that live in a multi-chamber spiral curved shell. Representatives of this genus are the only direct descendants of the oldest externally shell cephalopods.
Modern octopuses are very diverse: from the giant North Pacific octopus (Enteroctopus dofleini), in which only one tentacle can reach two meters in length, to the tiny Octopus wolfi, whose mass does not exceed 30 grams. Shallow-water species prefer to settle among corals, stay in muddy creeks or hide in the sand, surfacing only to get from one point to another, or fleeing predators. Views of the open sea cut through the open spaces, following the ocean currents. They are found everywhere – from the tropics to the polar regions.
Let us return, however, to the shores of the island of Lembekh. A new day is just beginning, the sun’s rays penetrate the water column. You are floating over a shallow coral reef. The local guide Amba gives you a sign that he noticed an octopus, and quite a large one. You look around, trying in vain to make out a mollusk, but you see only rocks covered with corals and motley sponges. Amba insists, gesturing: “Big!”. You look where he pokes a finger, but you don’t see anything. However, once again looking at the dark velvety coral, you understand that this is not coral, but a blue octopus (Octopus cyanea). And how you did not immediately make out this creature, the size of a serving dish!
Many animals are hiding, merging with the objects surrounding them – for example, that orange sponge over there is actually not a sponge, but a anglerfish, hiding in anticipation of careless prey. A leaf floating at the bottom is not a leaf at all, but also a fish pretending to be a leaf. Bright sea anemone is by no means a poisonous polyp, but a harmless sea slug that cleverly confuses everyone with its appearance. But a small section of the seabed suddenly took and swam – in fact it is a flounder, merged in color with the ground.
But even in such a company, octopuses and cuttlefish (and also, to a lesser extent, squid) have no equal in the art of disguising themselves on the fly, or rather, afloat – they look like coral, then like a ball of snakes, and the next minute they can’t be discerned on the sandy bottom. They adapt so skillfully to the surrounding objects that it seems as though they are using the body and skin to create three-dimensional images of various objects. How do they do it?
Octopuses have three degrees of protection (disguise). The first is color mimicry – pigments and reflectors are used for it. Pigments are granules of yellow, brown and red color and are located inside numerous sacs in the upper layer of the skin (there can be several thousand, and when closed they look like tiny specks). To change color, the mollusk compresses the muscles around the sacs, squeezing them out, where they expand. Cleverly managing the size of the bags, the octopus is able to change patterns on the skin – from spots to wavy lines and stripes. Reflective cells are of two types: the first simply reflect the rays incident on them – in white light they are white, in red light blush. Cells of the second type are similar to a soap bubble film: they shine in different colors depending on the angle of incidence of light rays.
The second element of the masking system is the texture of the skin. By activating certain muscle groups, octopuses easily turn a smooth surface of the body into a knobby or even spiky one. For example, prickly abdopus (Abdopus aculeatus) imitates algae so plausibly that it is almost impossible to distinguish it from a plant without some skill.
The third secret, thanks to which the octopuses manage to go unnoticed, is a soft body that can turn into anything. For example, curl up in a ball and slowly move along the bottom, depicting a piece of a coral reef: “Like, I’m not a predator, but just a lifeless block.”
I wonder if octopuses understand what needs to be portrayed at any given moment? An ordinary freshwater snail has about 10 thousand neurons, lobsters – about 100 thousand, and horse spiders – 600 thousand. Bees and cockroaches, leading in the number of neurons among invertebrates – naturally, after cephalopods – have about a million. The nervous system of an ordinary octopus (Octopus vulgaris) consists of 500 million neurons: this is a completely different level. By the number of neurons, it significantly exceeds mice (80 million), as well as rats (200 million) and can easily be compared with cats (700 million). However, unlike vertebrates, in which most neurons are concentrated in the brain, in cephalopods, two-thirds of all nerve cells are concentrated in tentacles. Another important fact: the higher the level of development of the nervous system, the more energy the body spends on its functioning, so the benefits should be worth it. Why do octopuses need 500 million neurons?
Peter Godfrey-Smith is a philosopher by education, but now studies octopuses at the City University of New York and at the University of Sydney. He believes that the emergence of such a complex nervous system is due to several reasons. Firstly, this is the structure of the body of the octopus – after all, the nervous system is transformed with the development of the whole organism, and the body of the octopus is extremely complex. The mollusk can turn any part of the tentacle wherever it wants (it does not have bones, which means there are no limiting joints). Thanks to this, octopuses have complete freedom of movement. In addition, each tentacle is able to move independently of the rest.
It is very interesting to watch the octopus during the hunt – it lies on the sand with spread tentacles, and each of them carefully examines and searches the area allocated to it, without missing a single hole. As soon as one of the “hands” stumbles upon something edible, for example, shrimp, two neighboring ones immediately rush to the rescue so as not to miss the prey. Suction cups on tentacles can also move independently of each other. Add to this the need for constant control of the color and texture of the skin; processing a continuous stream of information coming from the sensory organs – taste and tactile receptors on the suction cups, spatial orientation organs (statocysts), and also from very complex eyes – and you will understand why the cephalopod is such a developed brain.
The octopus also needs a complex nervous system for navigation, because its habitat – coral reefs – has a rather complex spatial structure. In addition, the mollusks do not have a shell, so you have to constantly be on the lookout and watch for predators, because if the camouflage does not work suddenly, you will need to “make legs” right away to take refuge in the shelter. “These animals are walking pieces of meat, a kind of filet mignon in the deep sea,” explains Mark Norman, a world-class expert on modern cephalopods from the Victoria Museum in Melbourne. And finally, octopuses are fast agile hunters with a wide range of taste preferences. They eat everything from oysters hiding in powerful shells, and ending with fish and crabs, which themselves do not miss: with strong claws or with sharp teeth.
So, a boneless body, a difficult habitat, a varied diet, the need to hide from predators – these are the main reasons, according to Peter Godfrey-Smith, and led to the development of mental abilities of cephalopods.
Being the owners of such a developed nervous system, how smart are they? Assessing the level of animal intelligence is not an easy task, often during such experiments we learn more about ourselves than about the individuals studied. The traditional signs that assess the presence of intelligence in birds and mammals, such as the ability to use tools, are not suitable in the case of octopuses, because the main tool in these mollusks is their own body. Why would an octopus craft something to extract goodies from an inaccessible crevice or use foreign objects to uncover an oyster? For all this, he has tentacles.
Tentacles are tentacles, but back in the 1950s and 1960s, scientists began to conduct experiments in which they found that octopuses are well trained and have good memory – these are two main signs of intelligence. Roy Caldwell, an octopus student at the University of California, Berkeley, says: “Unlike the smartest ordinary octopus (Octopus vulgaris), many of my wards were dumb like corks.” “Who is this?” – we ask. “For example, the tiny Octopus bocki.” “Why are they not so developed?” “Most likely, because in life they don’t have to deal with difficult situations.”
It doesn’t matter whether smart octopuses or stupid ones think about food or think in spiritual categories – in any case, they have something special. Something fascinating and alluring …
One more dive left. On Lembeh Island, sunset time. You stopped at the bottom of a rocky slope. A couple of fish are swimming in front of you, they are spawning. Not far from them, curled up, an eel hammered into the hole. The large hermit crab slowly drags its shell, and it taps on the bottom deadly. A small octopus lurks on a rock. You decided to take a closer look at him: now he begins to move slowly, for a moment hangs in the water column, like an eight-armed yogi. Then he glides back on his business. Now he has already climbed over the rock, but you still could not see how exactly he is moving, either pulling himself with his front tentacles, or pushing himself with his back. Continuing the movement, the mollusk gropes for a small crevice and instantly disappears there. Well, gone. No, not at all: a tentacle protrudes from the gap – checks the space surrounding the hole, grabs a few pebbles and closes the entrance with them. Now you can sleep peacefully.
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