''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 eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...

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 branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

, and refers to its general shape: namely, a teardrop-shaped cell with a small "head" at the end of a long slender "neck". The protist is notable for its ability to extend the anterior end of the cell up to 7 times its body length, and manipulate in many directions — even around obstacles — in order to capture its food. Richard L. Howey, Ken Jones, Roy Winsb
Lacrymaria Olor: Tear of a Swan
Accessed on 2009-12-04. For that reason it is a popular subject for amateur microscopists. The classification has been attributed to Müller (1786). Ward and Whipple, ''Fresh-water Biology''. Cited by Howey. 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 Micronucleus is the name given to the 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 i ...

. Its entire cell body is covered with cilia arranged in spirals. It has two contractile

vacuole A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic m ...

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

birefringent Birefringence 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 said to be birefringent (or birefractive). The 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, macro ...

s. ''Lacrymaria olor'' can be easily reproduced in vitro, but cultivated populations are difficult to maintain for long. It can reproduce sexually, 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 macro-organisms such as fungi. Definition Mating types are the microorganism equivalent to ...

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

genome In the fields of molecular biology and genetics, 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 g ...

; 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 is compiled from existing trusted databases curated by experts and with the assistance of ...

. Accessed on 2009-12-04. Species described in 1786 Litostomatea {{ciliate-stub

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References