Lacrymaria olor is a protozoan, typically 100 um long, that is found in freshwater ponds. Its name means "swan tear" in Latin

Latin

Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

, and refers to its general shape: namely, a teardrop-shaped body with a small "head" at the end of a long slender "neck". The animal is notable for its ability to extend the neck up to 7 times its body length, and manipulate in many directions — even around obstacles — in order to capture its food. For that reason it is a popular subject for amateur microscopists

Microscopy

Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...

. The classification has been attributed to Müller (1786).

The protozoan usually has two macronuclei

Macronucleus

A macronucleus is the larger type of nucleus in ciliates. Macronuclei are polyploid and undergo direct division without mitosis. It controls the non-reproductive cell functions, the everyday tasks, such as metabolism...

 and a single micronucleus

Micronucleus

A the micronucleus is the smaller nucleus in ciliate protozoans, such as the paramecium. In fission it divides by mitosis, and in conjugation furnishes the pairing of gamete nuclei, by whose reciprocal fusion a zygote nucleus is formed, which gives rise to the macronuclei and micronuclei of the...

. Its body, neck, and head are covered with cilia arranged in spirals. It has two contratile vacuoles

Vacuole

A vacuole is a membrane-bound organelle which is present in all 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 molecules including enzymes in solution, though in certain...

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

Birefringence

Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...

 crystal

Crystal

A crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are arranged in an orderly repeating pattern extending in all three spatial dimensions. The scientific study of crystals and crystal formation is known as crystallography...

s.

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

Sexual reproduction

Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...

, with each individual assuming either of two mating type

Mating type

Mating types occur in eukaryotes that undergo sexual reproduction via isogamy. Since the gametes of different mating types look alike, they are often referred to by numbers, letters, or simply "+" and "-" instead of "male" and "female." Mating can only take place between different mating...

s ("sexes") at various times of the day. It can also reproduce asexually

Asexual reproduction

Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...

, possibly after an internal rearrangement of its genome

Genome

In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....

; 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 animals such as ciliates, flagellates, and amoeba, but may sometimes tear chunks out of larger ciliates.