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Animalcule ("little animal", from Latin animal + the diminutive suffix -culum) is an older term for a microscopic animal or protozoan. The concept appears to have been proposed at least as early as around 30 BC, as evidenced by this translation from Marcus Varro's Rerum Rusticarum Libri Tres:

Animal Kingdom of motile multicellular eukaryotic heterotrophic organisms

Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres (110 ft). They have complex interactions with each other and their environments, forming intricate food webs. The kingdom Animalia includes humans, but in colloquial use the term animal often refers only to non-human animals. The study of non-human animals is known as zoology.

Protozoa Diverse motile unicellular heterotrophic eukaryotic organisms

Protozoa is an informal term for single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris. Historically, the protozoa were regarded as "one-celled animals", because they often possess animal-like behaviors, such as motility and predation, and lack a cell wall, as found in plants and many algae. Although the traditional practice of grouping protozoa with animals is no longer considered valid, the term continues to be used in a loose way to identify single-celled organisms that can move independently and feed by heterotrophy.

"Note also if there be any swampy ground, both for the reasons given above, and because certain minute animals, invisible to the eye, breed there, and, borne by the air, reach the inside of the body by way of the mouth and nose, and cause diseases which are difficult to be rid of." [1]

Some better-known animalcules include:

Actinophryid order of protists

The actinophryids are an order of heliozoa. They are the most common heliozoa in fresh water and can also be found in marine and soil habitats. Actinophryids are unicellular and roughly spherical in shape, with many axopodia that radiate outward from the cell body. Axopodia are a type of pseudopodia that are supported by hundreds of microtubules arranged in a needle-like internal structure. These axopods adhere to passing prey and assist with cell movement, as well as playing a part in cell division and cell fusion.

Heliozoa order of protists

Heliozoa, commonly known as sun-animalcules, are microbial eukaryotes (protists) with stiff arms (axopodia) radiating from their spherical bodies, which are responsible for their common name. The axopodia are microtubule-supported projections from the amoeboid cell body, and are variously used for capturing food, sensation, movement, and attachment. They are similar to Radiolaria, but they are distinguished from them by lacking central capsules and other complex skeletal elements, although some produce simple scales and spines. They may be found in both freshwater and marine environments.

<i>Amoeba proteus</i> species of Tubulinea

Amoeba proteus , alternatively Chaos diffluens, is an amoeba closely related to the giant amoebae and a species commonly bought at science supply stores.

The term was also used in the 17th century by Henry Oldenburg, the first Secretary of the Royal Society and founding editor of Philosophical Transactions , to translate the Dutch words used by Anton van Leeuwenhoek to describe microorganisms that he discovered. [2]

Henry Oldenburg German theologian

Henry Oldenburg FRS was a German theologian known as a diplomat, a natural philosopher and as the creator of scientific peer review. He was one of the foremost intelligencers of Europe of the seventeenth century, with a network of correspondents to rival those of Fabri de Peiresc, Marin Mersenne and Ismaël Boulliau. At the foundation of the Royal Society he took on the task of foreign correspondence, as the first Secretary.

Royal Society National academy of science in the United Kingdom

The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national Academy of Sciences. Founded on 28 November 1660, it was granted a royal charter by King Charles II as "The Royal Society". It is the oldest national scientific institution in the world. The society fulfils a number of roles: promoting science and its benefits, recognising excellence in science, supporting outstanding science, providing scientific advice for policy, fostering international and global co-operation, education and public engagement. It also performs these roles for the smaller countries of the Commonwealth.

The word appears in adjectival form in the "Major-General's Song", in which Major-General Stanley sings, "I know the scientific names of beings animalculous..." [3]

Major-Generals Song song

"I Am the Very Model of a Modern Major-General" is a patter song from Gilbert and Sullivan's 1879 comic opera The Pirates of Penzance. Sung by Major General Stanley at his first entrance, towards the end of Act I, the character introduces himself by presenting his résumé and admitting to a few shortcomings. The song satirises the idea of the "modern" educated British Army officer of the latter 19th century. It is difficult to perform because of the fast pace and tongue-twisting nature of the lyrics.

Binomial nomenclature System of identifying species of organisms using a two-part name

Binomial nomenclature, also called binominal nomenclature or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages. Such a name is called a binomial name, a binomen, binominal name or a scientific name; more informally it is also called a Latin name.

A 1795 illustration of van Leeuwenhoek's animalcules by an unknown artist Animalcules observed by anton van leeuwenhoek c1795 1228575.jpg
A 1795 illustration of van Leeuwenhoek's animalcules by an unknown artist

See also

Related Research Articles

Natural theology, once also termed physico-theology, is a type of theology that provides arguments for the existence of God based on reason and ordinary experience of nature.

Antonie van Leeuwenhoek Dutch tradesman and scientist

Antonie Philips van Leeuwenhoek was a Dutch businessman and scientist in the Golden Age of Dutch science and technology. A largely self-taught man in science, he is commonly known as "the Father of Microbiology", and one of the first microscopists and microbiologists. Van Leeuwenhoek is best known for his pioneering work in microscopy and for his contributions toward the establishment of microbiology as a scientific discipline.

An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It may react negatively or even die if free oxygen is present. In contrast, an aerobic organism (aerobe) is an organism that requires an oxygenated environment. Anaerobes may be unicellular or multicellular.

Cell theory scientific theory that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells

In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all organisms and also the basic unit of reproduction. With continual improvements made to microscopes over time, magnification technology advanced enough to discover cells in the 17th century. This discovery is largely attributed to Robert Hooke, and began the scientific study of cells, also known as cell biology. Over a century later, many debates about cells began amongst scientists. Most of these debates involved the nature of cellular regeneration, and the idea of cells as a fundamental unit of life. Cell theory was eventually formulated in 1839. This is usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientists like Rudolf Virchow contributed to the theory. It was an important step in the movement away from spontaneous generation.

Germ theory of disease Prevailing theory about diseases

The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to see without magnification, invade humans, other animals, and other living hosts. Their growth and reproduction within their hosts can cause disease. "Germ" may refer to not just a bacterium but to any type of microorganism or even non-living pathogen that can cause disease, such as protists, fungi, viruses, prions, or viroids. Diseases caused by pathogens are called infectious diseases. Even when a pathogen is the principal cause of a disease, environmental and hereditary factors often influence the severity of the disease, and whether a potential host individual becomes infected when exposed to the pathogen.

Marcus Terentius Varro ancient Latin scholar

Marcus Terentius Varro was an ancient Roman scholar and writer. He is sometimes called Varro Reatinus to distinguish him from his younger contemporary Varro Atacinus.

Fauna (deity) Roman goddess; either the wife, sister, or daughter of Faunus

In ancient Roman religion, Fauna[fau̯na] is a goddess said in differing ancient sources to be the wife, sister, or daughter of Faunus. Varro regarded her as the female counterpart of Faunus, and said that the fauni all had prophetic powers. She is also called Fatua or Fenta Fauna.

<i>Exoticorum libri decem</i> book by Carolus Clusius

Exoticorum libri decem is an illustrated zoological and botanical compendium in Latin, published at Leiden in 1605 by Charles de l'Écluse.

Preformationism formerly-popular theory that organisms develop from miniature versions of themselves

In the history of biology, preformationism is a formerly-popular theory that organisms develop from miniature versions of themselves. Instead of assembly from parts, preformationists believed that the form of living things exist, in real terms, prior to their development. It suggests that all organisms were created at the same time, and that succeeding generations grow from homunculi, or animalcules, that have existed since the beginning of creation.

Microbiology Study of microscopic organisms

Microbiology is the study of microorganisms, those being unicellular, multicellular, or acellular. Microbiology encompasses numerous sub-disciplines including virology, parasitology, mycology and bacteriology.

Nenia Dea Roman goddess

Nenia Dea was an ancient funeral deity of Rome, who had a sanctuary outside of the Porta Viminalis. The cult of the Nenia is doubtlessly a very old one, but according to Georg Wissowa the location of Nenia's shrine (sacellum) outside of the center of early Rome indicates that she didn't belong to the earliest circle of Roman deities. In a different interpretation her shrine was located outside of the old city walls, because it had been custom for all gods connected to death or dying.

Axia (gens) families from Ancient Rome who shared the Axius nomen

The gens Axia, also spelled Axsia, was a plebeian family at Rome during the final century of the Republic and the beginning of the Empire. The gens does not appear to have been particularly large or important, although at least some of the family were reasonably wealthy.

The gens Modia was a minor family at Ancient Rome, known from a small number of individuals.

The gens Cossinia was a plebeian family at Rome. The gens originated at Tibur, and came to Rome early in the first century BC. None of its members ever obtained the higher offices of the state.

Fundania (gens) families from Ancient Rome who shared the Fundanius nomen

The gens Fundania was a plebeian family at Ancient Rome, which first appears in history in the second half of the third century BC. Although members of this gens occur well into imperial times, and Gaius Fundanius Fundulus obtained the consulship in BC 243, the Fundanii were never amongst the more important families of the Roman state.

Antigonus of Cumae in Asia Minor was an ancient Greek writer on agriculture, who is referred to by Pliny, Varro, and Columella, but whose age is unknown.

The gens Hirria was a minor Roman family, appearing in history during the final century of the Republic, and in Imperial times. It is chiefly remembered as the result of Gaius Hirrius, a farmer of lampreys in the time of Caesar.

The gens Laenia was a minor family at Rome during the first century BC. It is remembered chiefly from two individuals, one a friend of Varro, the other of Cicero. Both had houses at Brundisium, suggesting either that the family came from that region, or that the individuals mentioned were closely related.

The gens Luciena was a minor family at Rome. Members of this gens are first mentioned in the final century of the Republic.

Georg Goetz German classical philologist

Georg Goetz was a German classical philologist, known for his scholarly treatment of Plautus and Varro.


  1. Storr-Best, Lloyd (1912). Varro on farming. M. Terenti Varronis Rerum rusticarum libri tres. London: G. Bell and Sons. p. 39.
  2. Anderson, Douglas. "Animalcules". Lens on Leeuwenhoek. Retrieved 9 October 2019.
  3. "I Am the Very Model of a Modern Major-General". Paragraph #2.CS1 maint: others (link)