Dileptus anser
Encyclopedia
Dileptus anser is a unicellular ciliate
protozoan
belonging to the genus Dileptus
. Specimens range in size between 0.24 and 0.60 mm long, and are found in freshwater streams, lakes and ponds.
's trunk in its shape and flexibility, but with a flattened rather than round cross-section; and a flat triangular "tailfin", relatively stiff but steerable, which looks like a sharp thorn in top view. The body usually contains a row of two or more contractile vacuole
s along the dorsal
surface, numerous macronuclei
and hundreds of micronuclei
.
) Most of the proboscis may be lost in this way during a feeding period, but is regenerated before the next period. Captured prey is ingested by a "mouth" (cytosome) that opens wide near the base of the trunk. It may however ingest prey directly even without using the proboscis. The mouth is surrounded by toxicysts that sting and paralyze the prey.
and sexually
. It has three distinct mating types ("sexes"), conventionally designated I, II, and III. Individuals may go through several mating types in the course of their lives. However the final and (usually) stable type is genetically determined by a single genetic locus mat with three three allele
s, one for each type, with type I being dominant over type II, and II over III.
Ciliate
The ciliates are a group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagella but typically shorter and present in much larger numbers with a different undulating pattern than flagella...
protozoan
Protist
Protists are a diverse group of eukaryotic microorganisms. Historically, protists were treated as the kingdom Protista, which includes mostly unicellular organisms that do not fit into the other kingdoms, but this group is contested in modern taxonomy...
belonging to the genus Dileptus
Dileptus
Dileptus is a genus of unicellular ciliate protists, belonging to the class Litostomatea. Members of the genus are found in fresh and salt water...
. Specimens range in size between 0.24 and 0.60 mm long, and are found in freshwater streams, lakes and ponds.
Morphology
Dileptus anser has a "body" shaped like an elongated pear, wider in the front part; a broad and tapering "proboscis", reminiscent of an elephantElephant
Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...
's trunk in its shape and flexibility, but with a flattened rather than round cross-section; and a flat triangular "tailfin", relatively stiff but steerable, which looks like a sharp thorn in top view. The body usually contains a row of two or more contractile vacuole
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...
s along the dorsal
Dorsum (biology)
In anatomy, the dorsum is the upper side of animals that typically run, fly, or swim in a horizontal position, and the back side of animals that walk upright. In vertebrates the dorsum contains the backbone. The term dorsal refers to anatomical structures that are either situated toward or grow...
surface, numerous 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 hundreds of micronuclei
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...
.
Feeding habits
Dileptus anser feeds upon other unicellular organisms, almost exclusively in the early morning, between 4am and 9am. It uses its proboscis to strike the prey. The tip of the proboscis may become adhesive, and may be detached if it gets stuck on a larger object (such as a microscope slideMicroscope slide
A microscope slide is a thin flat piece of glass, typically 75 by 25 mm and about 1 mm thick, used to hold objects for examination under a microscope. Typically the object is placed or secured on the slide, and then both are inserted together in the microscope for viewing...
) Most of the proboscis may be lost in this way during a feeding period, but is regenerated before the next period. Captured prey is ingested by a "mouth" (cytosome) that opens wide near the base of the trunk. It may however ingest prey directly even without using the proboscis. The mouth is surrounded by toxicysts that sting and paralyze the prey.
Reproduction
Like most ciliates, Dileptus anser can reproduce both asexuallyAsexual 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...
and 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...
. It has three distinct mating types ("sexes"), conventionally designated I, II, and III. Individuals may go through several mating types in the course of their lives. However the final and (usually) stable type is genetically determined by a single genetic locus mat with three three allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s, one for each type, with type I being dominant over type II, and II over III.
See also
- DileptusDileptusDileptus is a genus of unicellular ciliate protists, belonging to the class Litostomatea. Members of the genus are found in fresh and salt water...
- Lacrymaria olorLacrymaria olorLacrymaria olor is a protozoan, typically long, that is found in freshwater ponds. Its name means "swan tear" in Latin, and refers to its general shape: namely, a teardrop-shaped body with a small "head" at the end of a long slender "neck"...
, another protist with a flexible and extensible "neck". - Dileptus aculeatus (Dragesco, 1960)