''Lacrymaria olor'' is a species of

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

s, typically long, that is found in freshwater ponds. Its name means "swan tear" in

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

, and refers to its general shape: namely, a teardrop-shaped cell with a small "head" at the end of a long slender "neck". The classification has been attributed to Müller (1786). The

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

is notable for its ability to extend its "neck" by up to thirty times the length of its body (about 1.2 mm), and manipulate in many directions very rapidly — even around obstacles — in order to capture its food. Such extension is not in and of itself unique, but the organism's ability to do the extension quickly and repeatedly sets it apart from others. The molecular mechanism underlying ''L. olor'''s "cellular origami" appears to be a helical array of microtubules, presently unique among organisms, uncovered in 2024. The protist usually has two

macronuclei A macronucleus (formerly also meganucleus) is the larger type of nucleus in ciliates. Macronuclei are polyploid and undergo direct division without mitosis. It controls the non-reproductive cell functions, such as metabolism. During conjugation, t ...

and a single

micronucleus A micronucleus is a small nucleus that forms whenever a chromosome or a fragment of a chromosome is not incorporated into one of the daughter nuclei during cell division. It usually is a sign of genotoxic events and chromosomal instability. Mic ...

. Its entire cell body is covered with

cilia The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

arranged in spirals. It has two contractile

vacuole A vacuole () is a membrane-bound organelle which is present in Plant cell, plant and Fungus, fungal Cell (biology), cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water ...

s, one at each end of the body. It contains small

birefringent Birefringence, also called double refraction, is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are described as birefring ...

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s. ''Lacrymaria olor'' can be easily reproduced in vitro, but cultivated populations are difficult to maintain for long. It can

reproduce sexually Sexual reproduction is a type of reproduction that involves a complex Biological life cycle, life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another gamete to p ...

, with each individual assuming either of two

mating type Mating types are the microorganism equivalent to sexes in multicellular lifeforms and are thought to be the ancestor to distinct sexes. They also occur in multicellular organisms such as fungi. Definition Mating types are the microorganism equival ...

s ("sexes") at various times of the day. It can also reproduce asexually, possibly after an internal rearrangement of its

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

; but there is evidence that this mechanism stops working after a certain number of consecutive asexual generations. It can also regenerate a new head within minutes, if the original is cut off. ''Lacrymaria'' feed primarily on smaller organisms such as other ciliates, flagellates, and amoeba, but may sometimes tear chunks out of larger ciliates.

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References

Lacrymaria olor
page at the

Encyclopedia of Life The Encyclopedia of Life (EOL) is a free, online encyclopedia intended to document all of the 1.9 million living species known to science. It aggregates content to form "pages" for every known species. Content is compiled from existing trusted ...

. Accessed on 2009-12-04. Protists described in 1786 Litostomatea Ciliate species {{ciliate-stub

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References