The largest single-celled creature. Giants of the microbial world - the largest single-celled organisms
An ostrich egg, reaching 15 cm in height and weighing about 1.5 kg, is often cited as an example of the largest cell of living organisms, but this is a myth.
Contrary to popular belief, there are at least a few other types of living cells that are larger than an ostrich egg. It is possible that ostrich eggs may be the heaviest cells in nature, but tests have not yet been carried out.
If we talk about size and not weight, then an ostrich egg is not the largest cage. Much larger are the nerve cells of large animals like giant squids - their nerve cells can reach 12 meters in length, which is about 80 times larger than an ostrich egg.
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Despite the fact that most people eat the very obvious eggs of birds and fish almost every day, the words “single-celled organism” conjure up something that can only be seen through a microscope. Indeed, the vast majority of single-celled creatures do not exceed dimensions of hundredths of a millimeter, and this can be explained by a number of factors. It is more difficult for large living cells to maintain structural integrity, it is more difficult to transport food and waste within the body, in addition, impressive growth requires a fair amount of energy, which is evolutionarily disadvantageous.
But the world of microbes is rich in species, old and diverse, and therefore full of exceptions to the rules. And some organisms, to which the prefix “micro-” would be attached, despite the evolutionary benefit, do not achieve anything at all. Which, naturally, delights and fascinates.
Trumpeter ciliate
This freshwater creature resembles the trumpet of an ancient gramophone and grows up to 2 mm in length, so the trumpet ciliate can be studied without instruments. Protozoa of the genus Stentor are well known to microbial enthusiasts. Two millimeters does not seem super long, but many of nature's multicellular children take up much less space in their habitats and on glass slides.
What makes the trumpeter ciliate a colossus in the world of small fry is its anatomy. Unlike ordinary eukaryotes, Stentor contains not one, but several nuclei. This makes his daily work of maintaining his spirit easier. In the case of this ciliate, numerous small nuclei are responsible for reproduction, and the large nucleus - the macronucleus - manages everything else, playing the role of a kind of brain center.
The body of the trumpeter is covered with cilia of different lengths. Their friendly movements allow the ciliates to swim. These microcosm colossi feed on, for example, silt. The function of the mouth is performed by the narrow end of the “pipe”. At the same time, some bacteria, small protozoa, and even tiny unlucky multicellular organisms end up in the food.
Bahamas Thunder
One day, scientists from the University of Texas went to the bottom of the sea near the Bahamas and discovered there, in the gloomy depths, dozens of unusual spherical objects the size of grapes. These objects seemed motionless, but clearly left traces in the sand up to half a meter long. At first, experts thought about some unknown mollusks or even strangely behaving poop. The truth was amazing, because the mysterious piles turned out to be spherical protozoa with a diameter of up to 3 centimeters. Which rolled along the bottom of the sea in almost zero temperature water.
The Bahama Gromya is an amoeba-like organism with a shell that is soft and porous. Pseudopodia are inserted into the holes in it, with the help of which the gromia moves along the bottom, feeding on organic matter caught along the way.
The discovery of this creature changed some views on the evolution of living beings, since it was previously believed that multicellular animals with bilateral symmetry were the first to learn to crawl back in Precambrian times. And the traces that gromia leaves are very similar to ancient fossilized prints that are almost 2 billion years old.
Unfortunately, little is known about these cytoplasmic balls because it is very difficult to get live Gromia specimens into the laboratory. Despite their shells, protozoa are very fragile and vulnerable. Scientists say that they are much softer than grapes, which these giant microbes are somewhat similar to.
Acetabularia
Known as the “mermaid glass,” Acetabularia is a unique genus of green algae similar in shape to cap mushrooms. These plants of shallow tropical seas are up to 10 cm in length and usually grow in groups, attaching their legs to bottom stones and showing off their light green caps.
Typically, large single-celled creatures have more than one nucleus, which is not the case with the amazing Acetabularia, which spends most of its life with just one giant DNA container located at the base of its “stalk.” Only at the hour of reproduction are additional nuclei formed, migrating to the top of the algae, where they turn into spore-like cysts, which, after wintering and complex transformation, become young acetabularia. The life cycle of these colossal coenocytes is about three years.
In experiments carried out with Nazi money in the 1930s and 40s by German scientist Joachim Hammerling, it was found that after one species of acetabularia is transplanted with the nucleus of another species of algae, the original plant begins to form a new cap, transforming into an unusual hybrid.
In addition, the “glass from which mermaids drink” perfectly regenerates when damaged, which is very reminiscent of some multicellular species of the world of flora and fauna.
Bellied Valonia
Some call this funny shallow-water creature “the eye of a sailor,” others simply call it “a bubble algae.” Wallonia potbellied easily grows up to 4 cm in diameter and even more, one organism is one living cell with many nuclei, most often territorially solitary and always similar to a polished greenish pebble. Sometimes small “multicellular organisms” also take root on the surface of this unicellular marine miracle.
Despite the biological strangeness and exotic appearance of the algae, the pot-bellied wallonia is not favored by the owners of large marine aquariums. If a plant accidentally invades, it will take over the entire bottom, making it terribly difficult to get rid of. Crushing or tearing this tenacious weed into pieces is not the case, because it is through cell division that the pot-bellied wallonia with its “collection” of nuclei reproduces.
Caulerpa thyssolifolia
You might think about it as if it were some kind of fern, but in essence this plant is much simpler. And much more decisive in growth. What appears to an inexperienced diver to be thickets of underwater flora will actually turn out to be one or just a few living cells, “masquerading” as complex multicellular bushes. These primitive creatures are called "caulerpa taxifolia", or simply caulerpa herringbone, an amazing creeping thyssolid stem. One cell of this green algae, with its countless DNA stores, can very quickly expand almost three meters in width, which regularly happens in the Mediterranean Sea, destroying the healthy ecology of the depths there. For this reason, the herringbone caulerpa is recognized as a particularly harmful weed. In California, this “giant microbe” is generally considered an illegal species.
The Mediterranean variety of thyssolist caulerpa, whose cells reach record sizes, owes its status as a pest to humans. Just half a century ago, this unusual algae did not live at all in the Mediterranean Sea. But in the 1970s, an aquarium in Germany ordered specimens of caulerpa from the tropics, but not just for beauty and easy care. Inquisitive Germans subjected the “Christmas tree” to technical abuse. The macrophyte was irradiated with ultraviolet light and treated with chemical mutagens. The result was a single-celled monster, growing very quickly and resistant to low temperatures. The cold-resistant and attractive-looking algae was released into the Mediterranean Sea in 1980 - some amateur aquarist from Monaco tried.
In four years, the inevitable happened. After escaping from the aquarium, the mutated caulerpa victoriously occupied the coastal waters of the Mediterranean. Unlike its natural counterpart, the mutant cell turned out to be not only aggressive, but also resistant to pollution. Moreover, it is capable of regenerating from a piece only a centimeter in size. And poisonous. Attempts to clear the resort's shallow waters of caulerpa thickets failed.
Therefore, at the end of the 20th century, the nickname “killer algae” was assigned to the single-celled organism “Caulerpa taxifolia”. The plant is included in the hundred most dangerous invasive species, stopping the spread of which is the sacred duty of every concerned earthling.
Amoeba Chaos
Imagine an amoeba from a school textbook. Enlarge it to the size of a sesame seed. You will get the creature Chaos carolinensis. Since such protozoa constantly change shape, the champions among chaos are able to stretch up to 5 mm in length. Such heavy single-celled organisms can be fatally wounded simply by covering them with a microscope slide.
Despite its impressive size, Chaos carolinensis behaves in the same way as its microscopic pseudopod-bearing relatives. With the help of pseudopodia, chaos move, and they also grab food. The food in the vacuoles is then digested alive, and the remaining waste is thrown out of the cell to the outside. The huge amoeba feeds on microbes of other species, as well as small animals such as cladocerans. Chaos will eat almost non-stop until it is ready to reproduce.
Like its neighbors on the list of giants of the microbial world, unicellular chaos has many control centers, simply because one nucleus is not able to control such a massive cell. Depending on size, Chaos carolinensis can have up to 1000 nuclei.
Spirostomum
The ciliate spirostomum can be found and seen in both fresh and salt waters. And mistaken for some little worm. The elongated body of the spirostomum reaches a length of 4 millimeters. Only when looking through the microscope eyepiece does it become clear that this mobile creature is one large and very long cell, covered with a dense forest of cilia.
Spirostomum is the champion of the microbial world in its ability to change body volume. When disturbed, a ciliate can shrink by 75% in less than 1/200 of a second - faster than any other living cell.
Unlike the voracious trumpet ciliates, Spirostomum does not eat multicellular creatures, but only gets by on bacteria. Giants reproduce by simple division and really don’t like it if there are heavy metals in the water, which makes these ciliates friends of ecologists.
Siringammina is the most fragile
Another useful candidate for the title of the largest single-celled creature on Earth is a fragile “monster” from the xenophyophore class. This class of “carrying other people’s bodies” organisms includes many inhabitants of the ocean floor, clumps of cytoplasm that build for themselves in the eternal night fragile wicker “houses” from the remains of other creatures, for example, sponges or radiolarians. Xenophyophore cells make construction glue themselves, following commands coming chemically from numerous nuclei that float in massive clumps of cytoplasm. The largest of these clumps reaches 20 cm in size, is readily colonized by worms and bears the specific name Syringammina fragilissima.
Unfortunately, the life and biology of syringammina (“sand flute of Pan” in translation) is still poorly understood. Scientists suspect that this single-celled bacteria feeds, but no one has seen what the process itself looks like. There is an opinion that the fragile syringammina grows microbes for its diet within itself. The mechanism of reproduction of these rhizaria is also unclear.
The fragile deep-sea creatures were discovered in 1882 by the Scots, off their native North Sea shores. Subsequently, syringammin was found on the shelf of northern Africa.
Their name is legion...
Among the terrestrial single-celled giants, the meter-long slime molds, inhabitants of dead wood, deserve special attention, of course. Which at first and for a long time were mistaken for mushrooms.
However, slime molds (in particular, multi-headed Fusarium) turned out to be not only more primitive, but also in some ways much smarter than mushrooms. You can read about the interesting conclusions of Japanese scientists in this regard in the material.
The largest cell in the human body is the egg and, of course, it is found only in the body of women, since it is part of the female reproductive system. Its diameter is approximately 130 microns. It is generally accepted that an egg lives for about one month, but this is not true. A month is the time of its maturation. And the egg itself is 5-6 months older than the woman. How can this be? The fact is that even when the little girl is in the womb, between the 3rd and 6th months of intrauterine development, all her eggs are formed.
A newborn girl is born with a full set of immature eggs. She has about 100,000 of them. Approximately 250-400 of them will mature during a woman’s life, only a few of them will be fertilized and make the world happy with a new birth. All the rest will remain in an immature state.
Egg of the expectant mother
Eggs are greatly influenced by life factors: infections, chronic diseases, stress, depression, smoking, alcohol, taking heavy medications, etc. All this cannot pass without leaving a trace and has a strong impact on the unborn child. By the way, the older a woman gets, the older her eggs are. At the same time, their risk of genetic disorders increases. For example, for 30-year-old women, the risk of having a child with Down syndrome increases 4 times compared to 20-year-old women, and for 40-year-old women – 10 times.
According to doctors, women who want to give birth to a child after 35 years old should definitely consult a doctor, or even better, resort to the method of artificial insemination. It greatly reduces the chances of having a child with pathologies, since the egg is fertilized in the laboratory and is carefully examined for abnormalities even before it is implanted into the uterine cavity.
Description of sperm
The smallest cell in the human body is the sperm. It occurs only in men, because it is part of their reproductive system. The first sperm cells, like immature eggs in the body of women, are formed even when the unborn boy develops in the womb. The main life task of the cell is to overcome the woman’s reproductive tract and penetrate the egg to fertilize it. Together with the sperm, the man's genetic material is introduced into the egg.
The total length of the cell is 55 µm, the head is 5.0 µm in length and 3.5 µm in width, the middle section is 4.5 µm and the tail is 45 µm in length. This small size allows the sperm to move quickly. The cell moves with the help of a flagellum, while it rotates around its axis. Movement speed 3 mm/min. To fertilize a female cell, a sperm needs to travel a distance of about 20 centimeters.
Fertilization of the egg
In a man’s body, a sperm matures within 64 days and can remain alive for about a month. After entering a woman’s body, sperm die within about 2 hours. Having reached the uterine cavity, sperm can live up to three days, and at the same time maintain their motor activity, since the environment of the cavity supports their vital activity. According to scientists, in the uterine cavity the motor activity of sperm even increases.
The sperm then move down the fallopian tube against the flow of fluid. How they can find the egg is not yet known to science. There is a possibility that they rush towards the source of enzymes that are secreted by the egg. With pathology in men, the quantity and quality of sperm decreases, this is often the cause of infertility. The quality of sperm is also significantly affected by the environment and lifestyle of a man.
Rotifers - the smallest multicellular creatures on Earth. Although this creature is from 0.3 to 2 mm in size, the rotifer has muscular, digestive, excretory, nervous and reproductive systems.
And the most intricate and strange method of reproduction.
“Every living thing in nature has its own characteristics and its own oddities. The most curious creatures on Earth include tiny worms, which are commonly called rotifers, and in Latin Rotifera. They are found everywhere: in large and small lakes, reservoirs, ponds, ordinary puddles and even in the smallest droplets of water on plants. And despite such prevalence, almost no one knows them: the largest rotifers barely reach two millimeters, and they are mostly microscopic in size.
Even a large rotifer is not so easy to spot in a pond. Of course, you can see it under a microscope, but to do this you need to act quickly, that is, have time to grab the rotifer with a pipette along with a drop of water, place it in the recess of a glass slide, cover it with a coverslip and try not to break it. And then you will finally see the rotifer - this extremely complex organism.
No, this is not some kind of ciliate, although the rotifer is hardly larger than it; not a single-celled creature, not a slimy lump with cilia; It looks so inconspicuous, it has approximately the same structure as a person. It has a nervous system, sensory organs, muscles, glands, stomach, intestines, jaws, esophagus, kidneys, ovaries, genitals, etc. In addition, eyes and organs of touch. And this entire complex mechanism fits in a space no larger than a comma.
But it is naturally difficult to understand everything you see without certain knowledge. K. Wesenberg-Lund in “Notes of the Academy of Sciences” (1930) describes rotifers in great detail. I will try to convey the results of his scientific research.
Rotifer cells, unlike ours, do not divide. In each organ of an animal, their number remains unchanged throughout life: cells grow, but do not multiply; damaged tissue is not restored. Asexual reproduction such as budding, as in primitive organisms, is excluded from them.
For a long time it was believed that rotifers are hermaphrodites, like snails and leeches. Scientists examined mainly females, because males were simply not noticed: they are so small that they can easily pass through the finest mesh. These reduced organisms sometimes lack important organs - for example, the digestive system. Some of the dwarf males consist almost only of a powerful reproductive system and move with the help of cilia. Their lifespan is calculated in several hours. They reproduce in a very unusual way.
The French scientist E. Maupas, in his work from 1890–1891, first noticed the presence within the same species of rotifers of three forms: one male and two female. The first of them is a microscopic “he”, extremely simplified in its structure (lives only a few hours). The second form is the eternal virgins, they lay fragile eggs and give birth to females again. And the third one lays both unfertilized eggs (also with a thin shell), from which only males develop, and fertilized ones (black, strong, adapted for wintering), which give rise to new generations of virgin females. The German scientist O. Storch called females of the first type “amictic”, and the second - “mictic” (1924).
Some rotifers have only one mating season (summer), while others have two (spring and autumn). These days, tiny males dart through the water like arrows. In an aquarium, their clusters look like a whitish haze. Mating in rotifers is also unusual: the male inserts himself into the female’s body in any place he wishes. Wesemberg-Lund writes, for example, that it is quite common to see a female mating with two males, front and back. (This case was excellently illustrated by the German zoologist H. Kretschmer in the journal International Review, 1908, No. 1.)
So, first there are several generations of virgins who lay unfertilized eggs; when there are a lot of them in the reservoir, other females hatch, laying both unfertilized eggs (from which males develop), and fertilized ones - more hardy, capable of overwintering - which again supply virgin females.
Yes, you can hardly find stranger reproduction in nature.
Rotifers, of course, are for the most part simply invisible to us. However, one should not forget about these creatures when writing about life in a pond."
(c) Hans Scherfig "Pond"
Some ciliates-slippers are an order of magnitude larger than a rotifer, and sometimes a multicellular rotifer runs the risk of being devoured by a unicellular ciliate!
How many small creatures live on Earth, about which we know nothing. These creatures are both unicellular and multicellular. Multicellular creatures are larger in size than unicellular ones. That is why most of the smallest creatures on Earth are simplest organisms. This list contains the ten smallest organisms.
Sea Urchin Echinocyamus Scaber
In science, sea urchins are classified in the class Echinoidea. These creatures are found in the oceans and live even at depths of 5000 meters. These are very tiny creatures with a spherical shape and a spiny, round shell. Sea urchins come in a variety of colors, including blue, red, purple, green, olive, and various shades of brown. They are characterized by great diversity - approximately 950 species of sea urchins are classified at the moment, and they all have different sizes, as well as shells ranging from 3 - 10 cm. These creatures move very slowly and depend on seaweed. Their smallest species is called Echinocyamus scaber - it does not exceed 6 mm in size, being one of the smallest creatures on Earth.
Starfish Patiriella Parvivipara
Starfish belong to the class Asteroidea. These creatures live in oceans around the world at depths of up to 6,000 meters or more. The shape of the starfish is somewhat like a star, with a round disk in the center, and five limbs surrounding it. Some star species have more than five limbs and come in a variety of colors, including red, blue, brown, orange or gray. These creatures have the ability to regenerate limbs after being attacked by predators. The starfish feeds on a variety of prey and its life cycle is quite complex. Many species of this creature have been discovered, but the smallest of them is Patiriella Parvivipara, measuring 5 mm. It is most often found near South Australia.
Sea cucumber Psammothuria Ganapati
Species of Sea Cucumbers are marine animals that belong to the class Holothuroidea. These varieties have an elongated body, slightly reminiscent of a cucumber - hence the corresponding name. The Sea Cucumber has a single sexual gland and is found in all of the world's oceans, but is most widespread in the Asia-Pacific region. These types of creatures are also eaten by people, they are even raised on special farms. Sea cucumbers send hormonal signals to communicate with other creatures of their species. The Sea Cucumber comes in a variety of sizes, ranging from 10 to 30 centimeters in length. However, the smallest one is called Psammothuria ganapatii and is approximately 4mm in length. You can meet this baby on the coast of India
Beetle Scydosella Musawasensisis
Beetles are usually classified under the insect class and have two pairs of wings. These animals have the ability to survive in any environment. They are present everywhere, with the exception of marine and colder areas. These species can survive on any type of diet, including waste, fungi, plants, flesh and much more. Overall, there are more than forty thousand species of beetles around the world, ranging in size, but the smallest of these species, Scydosella musawasensis of the genus Nanosellini, is only 300 micrometers in length.
Nanoarchaeum bacterium
Nanoarchaeum equitans is a bacterium with a diameter of 400 nm. The organism requires a fairly high temperature for its full growth, and must always remain in contact with the host. Their small size of 400 nm makes them one of the smallest living creatures in the world.
Nanobacterium Nanobes
The newly discovered nanobacterium Nanobes is one-tenth the size of bacteria and is considered the tiniest life form on earth. They reach only 20 millimicrons in size and are rather poorly studied. Until now, little is known about their unconventional method of reproduction, as well as other details of the functioning of Nanobes.