Fragmentation in multicellular or colonial organisms is a form of

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the ...

or cloning, where an organism is split into fragments. Each of these fragments develops into mature, fully grown individuals that are clones of the original organism. The organism may develop specific organs or zones to shed or be easily broken off. If the splitting occurs without the prior preparation of the organism, both fragments must be able to regenerate the complete organism for it to function as reproduction. Fragmentation as a method of reproduction is seen in organisms such as filamentous cyanobacteria, molds,

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throu ...

s, acoel flatworms, some annelid worms and sea stars.

Fragmentation in various organisms

Molds,

yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constit ...

s and

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is ...

s, all of which are part of the

Fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

kingdom, produce tiny filaments called

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e. These hyphae obtain food and nutrients from the body of other organisms to grow and fertilize. Then a piece of hyphae breaks off and grows into a new individual and the cycle continues. Many

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.mycobiont A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.phycobiont A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.soredia and isidia). Larger fragments of the thallus may break away when the lichen dries or due to mechanical disturbances (see the section on reproduction in lichens).

Plants

Fragmentation is a very common type of

vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment or cutting of the parent plant or spe ...

in plants. Many

trees In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are u ...

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from tree ...

s, nonwoody perennials, and

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...

s form clonal colonies by producing new rooted shoots by

rhizomes In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ...

or stolons, which increases the diameter of the colony. If a rooted shoot becomes detached from the colony, then fragmentation has occurred. There are several other mechanisms of natural fragmentation in plants. *Production of specialized reproductive structures: A few plants produce

adventitious Important structures in plant development are buds, shoots, roots, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant a ...

plantlets on their leaves, which drop off and form independent plants, e.g. ''

Tolmiea menziesii ''Tolmiea menziesii'' () is a species of flowering plant in the family Saxifragaceae. It is known by the common names youth on age, pick-a-back-plant, piggyback plant, and thousand mothers. It is a perennial plant native to the West Coast of No ...

'' and '' Kalanchoe daigremontiana''. Others produce organs like bulbils and turions. *Easily lost parts that have high potential to grow into a complete plant: Some woody plants like the

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...

naturally shed twigs. This is termed cladoptosis. The lost twigs may form roots in a suitable environment to establish a new plant. River currents often tear off branch fragments from certain cottonwood species growing on riverbanks. Fragments reaching suitable environments can root and establish new plants. Some

cacti A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Gree ...

and other plants have jointed stems. When a stem segment, called a pad, falls off, it can root and form a new plant. Leaves of some plants readily root when they fall off, e.g. ''

Sedum ''Sedum'' is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species, subsequently reduced to 400–500. They are leaf succul ...

'' and '' Echeveria''. * Fragmentation is observed in

nonvascular plants Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water. Non-vascular plants include two distantly re ...

as well, for example, in liverworts and mosses. Small pieces of moss "stems" or "leaves" are often scattered by the wind, water or animals. If a moss fragment reaches a suitable environment, it can establish a new plant. They also produce gemmae, for example in the splash-cups of '' Marchantia polymorpha'', that are easily broken off and distributed. People use fragmentation to artificially propagate many plants via division, layering, cuttings,

grafting Grafting or graftage is a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion () while the lower part is called the rootstock. The succ ...

, micropropagation and

storage organ A storage organ is a part of a plant specifically modified for storage of energy (generally in the form of carbohydrates) or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have ...

s, such as

bulb In botany, a bulb is structurally a short stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs dur ...

corm A corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen underground plant stem that serves as a storage organ that some plants use to survive winter or other adverse conditions such as summer drought and heat (perennation). The word ' ...

tuber Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing ...

s and

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ...

Animals

Sponges Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

and

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

colonies naturally fragment and reproduce. Many species of

annelids The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecolog ...

and flatworms produce by this method. When the splitting occurs due to specific developmental changes, the terms orchiectomy, laparotomy, and

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is kno ...

are used. In'architomy' the animal splits at a particular point and the two fragments regenerate the missing organs and tissues. The splitting is not preceded by the development of the tissues to be lost. Before splitting, the animal may develop furrows at the zone of splitting. The headless fragment must regenerate a completely new head. In ' paratomy', the split occurs perpendicular to the antero-posterior axis and the split is preceded by the "pregeneration" of the anterior structures in the posterior portion. The two organisms have their body axis aligned i.e. they develop in a head to tail fashion. Budding is similar to paratomy except that the body axes need not be aligned: the new head may grow toward the side or even point backward (e.g. ''

Convolutriloba retrogemma ''Convolutriloba retrogemma'' is a reddish-brown flatworm 2 mm in length also commonly known as redbug, red planaria, rust flatworm, or simply red flatworm. It is a marine flatworm that gets energy from its endosymbiotic algae or from the c ...

'' an acoel flat worm).

Coral

Many types of

colonies can increase in number by fragmentation occurring naturally or artificially. Reef aquarium enthusiasts fragment

s for various purposes including shape control; sharing with others; regrowth experiments; and minimizing damage to natural coral reefs. Both hard and soft corals can be fragmented.

Genera 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 nomenclat ...

highly tolerant of fragmentation include ''

Acropora ''Acropora'' is a genus of small polyp stony coral in the phylum Cnidaria. Some of its species are known as table coral, elkhorn coral, and staghorn coral. Over 149 species are described. ''Acropora'' species are some of the major reef corals r ...

'', '' Montipora'', '' Pocillopora'', '' Euphyllia'', and '' Caulastraea'' among others. Most

sea anemone Sea anemones are a group of predatory marine invertebrates of the order Actiniaria. Because of their colourful appearance, they are named after the '' Anemone'', a terrestrial flowering plant. Sea anemones are classified in the phylum Cnidaria, ...

s reproduce through fragmentation via a variety of methods including longitudinal fission, where the original anemone splits across the middle forming two equal-sized anemones, and basal laceration, in which small parts of the animal split from the base to form new anemones.

Echinoderms

echinoderm An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the ...

s, the process is usually known as fissiparity (a term also used infrequently for biological fission in general). Some species can intentionally reproduce in this manner through

autotomy Autotomy (from the Greek ''auto-'', "self-" and ''tome'', "severing", αὐτοτομία) or self-amputation, is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-defense mechanism to elude ...

. This method is more common during the larval editing stages.{{cite book, author1=Helen Nilsson Sköld , author2=Matthias Obst , author3=Mattias Sköld , author4=Bertil Åkesson , editor1=Baruch Rinkevich , editor2=Valeria Matranga , title =Stem Cells in Marine Organisms, chapter =Stem Cells in Asexual Reproduction of Marine Invertebrates, publisher =Springer, year =2009, page=125, isbn = 978-90-481-2766-5, chapter-url =https://books.google.com/books?id=-eP2p0VF6VcC&q=Fissiparity&pg=PA125

Disadvantage of this process of reproduction

As this process is a form of asexual reproduction, it does not produce

genetic diversity Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species, it ranges widely from the number of species to differences within species and can be attributed to the span of survival for a species. It is dis ...

in the offspring. Therefore, these are more vulnerable to changing environments, parasites, and diseases.

References

Fertility medicine Asexual reproduction