''Microplana terrestris'' is a species of

free-living Free-living may refer to: * a non-parasitism, parasitic organism * a non-Sessility (zoology), sessile (or free-swimming) organism {{dab ...

, terrestrial

flatworm The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegme ...

in the order

Tricladida A planarian is one of the many flatworms of the traditional class Turbellaria. It usually describes free-living flatworms of the order Tricladida (triclads), although this common name is also used for a wide number of free-living platyhelmin ...

. It was first described in 1773 by the Danish naturalist Otto Friedrich Müller as ''Fasciola terrestris'', but has since been reassigned to the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

Microplana ''Microplana'' is a genus of land planarians found in Europe and Africa. Description Species of the genus ''Microplana'' are characterized by having an elongate, rounded body and generally only two eyes. The copulatory apparatus has a permanen ...

''.

Description

''Microplana terrestris'', like all

s, is an unsegmented, soft-bodied

bilaterian The Bilateria or bilaterians are animals with bilateral symmetry as an embryo, i.e. having a left and a right side that are mirror images of each other. This also means they have a head and a tail (anterior-posterior axis) as well as a belly an ...

without a

body cavity A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid. The two largest human body cavities are the ventral body cavity, and ...

, and with no specialized

circulatory The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...

respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gre ...

organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic keyboard instrument ** Hammond ...

s. Like other members of

Geoplanidae Geoplanidae is a family of flatworms known commonly as land planarians or land flatworms. These flatworms are mainly predators of other invertebrates, which they hunt, attack and capture using physical force and the adhesive and digestive proper ...

, it is dorso-ventrally flattened and creeps along with the whole of its ventral surface in contact with the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

. It is between in length and between wide. The anterior end is blunt and the colour is usually black or dark grey.

Distribution

''Microplana terrestris'' is native to Western Europe. Its range extends from Sweden in the north to the United Kingdom and Ireland and France, to Greece in the east. It requires a moist habitat. It has also been introduced into North America.

Ecology and behavior

Cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

provide the propulsive force when this flatworm moves. It can also produce stationary muscular waves along its body which can speed up its progression. It produces

mucus Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...

as it moves, and when using stationary waves, leaves intermittent "footprints" of slime. It can use its mucus trail as a "suspension bridge" to pass from one leaf to another. This flatworm is a generalist carnivore, feeding mostly on

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. ...

s, slugs,

snail A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class G ...

s and small

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...

s. It rarely attacks live, uninjured specimens, preferring to feed on dead or injured prey. Sexual reproduction occurs but it is able and frequently does reproduce without mating, producing cocoons containing several hatchlings. The first cocoon is produced 195 (±75) days after hatching and a further cocoon is produced about once a month thereafter. In the laboratory, one individual lived for 39 months. This flatworm is able to regenerate after being cut into two pieces, although it appears to greatly reduce its longevity.

References

{{Authority control Geoplanidae Invertebrates of Europe Animals described in 1773 Taxa named by Otto Friedrich Müller