The Marchantiophyta are a division of non-vascular land plants referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information, it is estimated. Some of the more familiar species grow as a flattened leafless thallus, but most species are leafy with a form much like a flattened moss. Leafy species can be distinguished from the similar mosses on the basis of a number of features, including their single-celled rhizoids. Leafy liverworts differ from most mosses in that their leaves never have a costa and may bear marginal cilia. Other differences are not universal for all mosses and liverworts, but the occurrence of leaves arranged in three ranks, the presence of deep lobes or segmented leaves, or a lack of differentiated stem and leaves all point to the plant being a liverwort. Liverworts are small from 2–20 mm wide with individual plants less than 10 cm long, are therefore overlooked.
However, certain species may cover large patches of ground, trees or any other reasonably firm substrate on which they occur. They are distributed globally in every available habitat, most in humid locations although there are desert and Arctic species as well; some species can be a weed in gardens. Most liverworts are small, measuring from 2–20 millimetres wide with individual plants less than 10 centimetres long, so they are overlooked; the most familiar liverworts consist of a prostrate, ribbon-like or branching structure called a thallus. However, most liverworts produce flattened stems with overlapping scales or leaves in two or more ranks, the middle rank is conspicuously different from the outer ranks. Liverworts can most reliably be distinguished from the similar mosses by their single-celled rhizoids. Other differences are not universal for all mosses and all liverworts. Unlike any other embryophytes, most liverworts contain unique membrane-bound oil bodies containing isoprenoids in at least some of their cells, lipid droplets in the cytoplasm of all other plants being unenclosed.
The overall physical similarity of some mosses and leafy liverworts means that confirmation of the identification of some groups can be performed with certainty only with the aid of microscopy or an experienced bryologist. Liverworts have a gametophyte-dominant life cycle, with the sporophyte dependent on the gametophyte. Cells in a typical liverwort plant each contain only a single set of genetic information, so the plant's cells are haploid for the majority of its life cycle; this contrasts with the pattern exhibited by nearly all animals and by most other plants. In the more familiar seed plants, the haploid generation is represented only by the tiny pollen and the ovule, while the diploid generation is the familiar tree or other plant. Another unusual feature of the liverwort life cycle is that sporophytes are short-lived, withering away not long after releasing spores. In other bryophytes, the sporophyte is persistent and disperses spores over an extended period; the life of a liverwort starts from the germination of a haploid spore to produce a protonema, either a mass of thread-like filaments or else a flattened thallus.
The protonema is a transitory stage in the life of a liverwort, from which will grow the mature gametophore plant that produces the sex organs. The male organs produce the sperm cells. Clusters of antheridia are enclosed by a protective layer of cells called the perigonium; as in other land plants, the female organs are known as archegonia and are protected by the thin surrounding perichaetum. Each archegonium has a slender hollow tube, the "neck", down which the sperm swim to reach the egg cell. Liverwort species may be either monoicous. In dioicous liverworts and male sex organs are borne on different and separate gametophyte plants. In monoicous liverworts, the two kinds of reproductive structures are borne on different branches of the same plant. In either case, the sperm must move from the antheridia where they are produced to the archegonium where the eggs are held; the sperm of liverworts is biflagellate, i.e. they have two tail-like flagellae that enable them to swim short distances, provided that at least a thin film of water is present.
Their journey may be assisted by the splashing of raindrops. In 2008, Japanese researchers discovered that some liverworts are able to fire sperm-containing water up to 15 cm in the air, enabling them to fertilize female plants growing more than a metre from the nearest male; when sperm reach the archegonia, fertilisation occurs, leading to the production of a diploid sporophyte. After fertilisation, the immature sporophyte within the archegonium develops three distinct regions: a foot, which both anchors the sporophyte in place and receives nutrients from its "mother" plant, a spherical or ellipsoidal capsule, inside which the spores will be produced for dispersing to new locations, a seta which lies between the other two
A fungus 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, separate from the other eukaryotic life kingdoms of plants and animals. A characteristic that places fungi in a different kingdom from plants and some protists is chitin in their cell walls. Similar to animals, fungi are heterotrophs. Fungi do not photosynthesize. Growth is their means of mobility, except for spores, which may travel through the water. Fungi are the principal decomposers in ecological systems; these and other differences place fungi in a single group of related organisms, named the Eumycota, which share a common ancestor, an interpretation, strongly supported by molecular phylogenetics. This fungal group oomycetes; the discipline of biology devoted to the study of fungi is known as mycology. In the past, mycology was regarded as a branch of botany, although it is now known fungi are genetically more related to animals than to plants.
Abundant worldwide, most fungi are inconspicuous because of the small size of their structures, their cryptic lifestyles in soil or on dead matter. Fungi include symbionts of plants, animals, or other fungi and parasites, they may become noticeable when fruiting, either as molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange in the environment, they have long been used in the form of mushrooms and truffles. Since the 1940s, fungi have been used for the production of antibiotics, more various enzymes produced by fungi are used industrially and in detergents. Fungi are used as biological pesticides to control weeds, plant diseases and insect pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals including humans; the fruiting structures of a few species contain psychotropic compounds and are consumed recreationally or in traditional spiritual ceremonies.
Fungi can break down manufactured materials and buildings, become significant pathogens of humans and other animals. Losses of crops due to fungal diseases or food spoilage can have a large impact on human food supplies and local economies; the fungus kingdom encompasses an enormous diversity of taxa with varied ecologies, life cycle strategies, morphologies ranging from unicellular aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of Kingdom Fungi, estimated at 2.2 million to 3.8 million species. Of these, only about 120,000 have been described, with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans. Since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christian Hendrik Persoon, Elias Magnus Fries, fungi have been classified according to their morphology or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits.
Phylogenetic studies published in the last decade have helped reshape the classification within Kingdom Fungi, divided into one subkingdom, seven phyla, ten subphyla. The English word fungus is directly adopted from the Latin fungus, used in the writings of Horace and Pliny; this in turn is derived from the Greek word sphongos, which refers to the macroscopic structures and morphology of mushrooms and molds. The word mycology is derived from the Greek logos, it denotes the scientific study of fungi. The Latin adjectival form of "mycology" appeared as early as 1796 in a book on the subject by Christiaan Hendrik Persoon; the word appeared in English as early as 1824 in a book by Robert Kaye Greville. In 1836 the English naturalist Miles Joseph Berkeley's publication The English Flora of Sir James Edward Smith, Vol. 5. Refers to mycology as the study of fungi. A group of all the fungi present in a particular area or geographic region is known as mycobiota, e.g. "the mycobiota of Ireland". Before the introduction of molecular methods for phylogenetic analysis, taxonomists considered fungi to be members of the plant kingdom because of similarities in lifestyle: both fungi and plants are immobile, have similarities in general morphology and growth habitat.
Like plants, fungi grow in soil and, in the case of mushrooms, form conspicuous fruit bodies, which sometimes resemble plants such as mosses. The fungi are now considered a separate kingdom, distinct from both plants and animals, from which they appear to have diverged around one billion years ago; some morphological and genetic features are shared with other organisms, while others are unique to the fungi separating them from the other kingdoms: Shared features: With other euka
Mycelium is the vegetative part of a fungus or fungus-like bacterial colony, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro within the fairy ring fungi. Fungal colonies composed of mycelium are found on soil and many other substrates. A typical single spore germinates into a homokaryotic mycelium. A mycelium may be minute, forming a colony, too small to see, or it may be extensive, as in Armillaria ostoyae: Is this the largest organism in the world? This 2,400-acre site in eastern Oregon had a contiguous growth of mycelium before logging roads cut through it.... Mushroom-forming forest fungi are unique in that their mycelial mats can achieve such massive proportions. Through the mycelium, a fungus absorbs nutrients from its environment, it does this in a two-stage process. First, the hyphae secrete enzymes onto or into the food source, which break down biological polymers into smaller units such as monomers; these monomers are absorbed into the mycelium by facilitated diffusion and active transport.
Mycelium is vital in terrestrial and aquatic ecosystems for their role in the decomposition of plant material. They contribute to the organic fraction of soil, their growth releases carbon dioxide back into the atmosphere. Ectomycorrhizal extramatrical mycelium, as well as the mycelium of Arbuscular mycorrhizal fungi increase the efficiency of water and nutrient absorption of most plants and confers resistance to some plant pathogens. Mycelium is an important food source for many soil invertebrates. "Mycelium", like "fungus", can be considered a mass noun, a word that can be either singular or plural. The term "mycelia", like "fungi", is used as the preferred plural form. Sclerotia are hard masses of mycelium. One of the primary roles of fungi in an ecosystem is to decompose organic compounds. Petroleum products and some pesticides are organic molecules, thereby show a potential carbon source for fungi. Hence, fungi have the potential to eradicate such pollutants from their environment unless the chemicals prove toxic to the fungus.
This biological degradation is a process known as bioremediation. Mycelial mats have been suggested as having potential as biological filters, removing chemicals and microorganisms from soil and water; the use of fungal mycelium to accomplish this has been termed mycofiltration. Knowledge of the relationship between mycorrhizal fungi and plants suggests new ways to improve crop yields; when spread on logging roads, mycelium can act as a binder, holding new soil in place and preventing washouts until woody plants can be established. Since 2007, a company called Ecovative Design has been developing alternatives to polystyrene and plastic packaging by growing mycelium in agricultural waste; the two ingredients are mixed together and placed into a mold for 3–5 days to grow into a durable material. Depending on the strain of mycelium used, they make many different varieties of the material including water absorbent, flame retardant, dielectric. In 2013, another company started producing mycelium bricks and mycelium leather.
Fungi are essential for converting biomass into compost, as they decompose feedstock components such as lignin, which many other composting microorganisms cannot. Turning a backyard compost pile will expose visible networks of mycelia that have formed on the decaying organic material within. Compost is an essential soil fertilizer for organic farming and gardening. Composting can divert a substantial fraction of municipal solid waste from landfills. Carbon sequestration Thallus Mycofiltration: A novel approach for the bio-transformation of abandoned logging roads Paul Stamets: Six ways mushrooms can save the world The mycelium Eben Bayer's Talk about Greensulate at the TED conference
An arbuscular mycorrhiza is a type of mycorrhiza in which the symbiont fungus penetrates the cortical cells of the roots of a vascular plant forming arbuscules. Arbuscular mycorrhizas are characterized by the formation of unique structures and vesicles by fungi of the phylum Glomeromycota. AM fungi help plants to capture nutrients such as phosphorus, sulfur and micronutrients from the soil, it is believed that the development of the arbuscular mycorrhizal symbiosis played a crucial role in the initial colonisation of land by plants and in the evolution of the vascular plants. It has been said that it is quicker to list the plants that do not form endomycorrhizae than those that do; this symbiosis is a evolved mutualistic relationship found between fungi and plants, the most prevalent plant symbiosis known, AMF is found in 80% of vascular plant families in existence today. The tremendous advances in research on mycorrhizal physiology and ecology over the past 40 years have led to a greater understanding of the multiple roles of AMF in the ecosystem.
This knowledge is applicable to human endeavors of ecosystem management, ecosystem restoration, agriculture. Both paleobiological and molecular evidence indicate that AM is an ancient symbiosis that originated at least 460 million years ago. AM symbiosis is ubiquitous among land plants, which suggests that mycorrhizas were present in the early ancestors of extant land plants; this positive association with plants may have facilitated the development of land plants. The Rhynie chert of the lower Devonian has yielded fossils of the earliest land plants in which AM fungi have been observed; the fossilized plants containing mycorrhizal fungi were preserved in silica. The Early Devonian saw the development of terrestrial flora. Plants of the Rhynie chert from the Lower Devonian were found to contain structures resembling vesicles and spores of present Glomus species. Colonized fossil roots have been observed in Aglaophyton major and Rhynia, which are ancient plants possessing characteristics of vascular plants and bryophytes with primitive protostelic rhizomes.
Intraradical mycelium was observed in root intracellular spaces, arbuscules were observed in the layer thin wall cells similar to palisade parenchyma. The fossil arbuscules appear similar to those of existing AMF; the cells containing arbuscules have thickened walls, which are observed in extant colonized cells. Mycorrhizas from the Miocene exhibit a vesicular morphology resembling that of present Glomerales; this conserved morphology may reflect the ready availability of nutrients provided by the plant hosts in both modern and Miocene mutualisms. However, it can be argued that the efficacy of signaling processes is to have evolved since the Miocene, this can not be detected in the fossil record. A finetuning of the signaling processes would improve coordination and nutrient exchange between symbionts while increasing the fitness of both the fungi and the plant symbionts; the nature of the relationship between plants and the ancestors of arbuscular mycorrhizal fungi is contentious. Two hypotheses are: Mycorrhizal symbiosis evolved from a parasitic interaction that developed into a mutually beneficial relationship.
Mycorrhizal fungi developed from saprobic fungi. Both saprotrophs and biotrophs were found in the Rhynie Chert, but there is little evidence to support either hypothesis. There is some fossil evidence that suggests that the parasitic fungi did not kill the host cells upon invasion, although a response to the invasion was observed in the host cells; this response may have evolved into the chemical signaling processes required for symbiosis. In both cases, the symbiotic plant-fungi interaction is thought to have evolved from a relationship in which the fungi was taking nutrients from the plant into a symbiotic relationship where the plant and fungi exchange nutrients. Increased interest in mycorrhizal symbiosis and the development of sophisticated molecular techniques has led to the rapid development of genetic evidence. Wang et al. investigated. These three genes could be sequenced from all major clades of modern land plants, including liverworts, the most basal group, phylogeny of the three genes proved to agree with current land plant phylogenies.
This implies that mycorrhizal genes must have been present in the common ancestor of land plants, that they must have been vertically inherited since plants colonized land. It was revealed that AM fungi have the bacterial type core enzyme of sRNA processing mechanism related with symbiosis, by the result of horizontal gene transfer from cyanobacterial ancestor; this finding of genetic fossil inside AM fungi raises the hypothesis of the intimate relationship between AM fungi and cyanobacterial ancestors. At the same time, Geosiphon-Nostoc symbiosis was reported previously. Despite their long time evolution as underground partner of the plant root of which environment is far from light or temperature fluctuation, AMF still have conserved circadian clock with its activation of fungal circadian oscillator by the blue light, similar to the case of the model circadian fungus Neurospora crassa; the proved conservation of circadian clock and output genes in R. irregulare opens the door to the study of circadian clocks in the fungal partner of AM symbiosis.
The characterized AMF frq gene by same research is the first frq gene identified outgroup of Dikarya, which suggest the frq gene evolution in fungal kingdom is much older than in
A parasitic plant is a plant that derives some or all of its nutritional requirement from another living plant. They make up about 1% of angiosperms and are in every biome in the world. All parasitic plants have modified roots, called haustoria, which penetrates the host plants, connecting them to the conductive system – either the xylem, the phloem, or both. For example, plants like Striga or Rhinanthus connect only to the xylem, via xylem bridges. Alternately, plants like Cuscuta and Orobanche connect only to the phloem of the host; this provides them with the ability to extract water and nutrients from the host. Parasitic plants are classified depending on where the parasitic plant latches onto the host and the amount of nutrients it requires; some parasitic plants are able to locate their host plants by detecting chemicals in the air or soil given off by host shoots or roots, respectively. About 4,500 species of parasitic plant in 20 families of flowering plants are known. Parasitic plants are characterized: 1a.
Obligate parasite – a parasite that cannot complete its life cycle without a host. 1b. Facultative parasite – a parasite that can complete its life cycle independent of a host. 2a. Stem parasite – a parasite that attaches to the host stem. 2b. Root parasite – a parasite that attaches to the host root. 3a. Hemiparasite – a plant parasitic under natural conditions, but photosynthetic to some degree. Hemiparasites may just obtain mineral nutrients from the host plant. 3b. Holoparasite - a parasitic plant that derives all of its fixed carbon from the host plant. Lacking chlorophyll, holoparasites are colors other than green. For hemiparasites, one from each of the three sets of terms can be applied to the same species, e.g. Nuytsia floribunda is an obligate root hemiparasite. Rhinanthus is a facultative root hemiparasite. Mistletoe is an obligate stem hemiparasite. Holoparasites are always obligate so only two terms are needed, e.g. Dodder is a stem holoparasite. Hydnora spp. are root holoparasites. Plants considered holoparasites include broomrape, dodder and the Hydnoraceae.
Plants considered hemiparasites include Castilleja, Western Australian Christmas tree, yellow rattle. Parasitic behavior evolved in angiosperms 12-13 times independently, a classic example of convergent evolution. 1% of all angiosperm species are parasitic, with a large degree of host dependence. The taxonomic family Orobanchaceae is the only family that contains both holoparasitic and hemiparasitic species, making it a model group for studying the evolutionary rise of parasitism; the remaining groups contain only holoparasites. The evolutionary event which gave rise to parasitism in plants was the development of haustoria; the first, most ancestral, haustoria are thought to be similar to that of the facultative hemiparasites within Tryphysaria, lateral haustoria develop along the surface of the roots in these species. Evolution led to the development of terminal or primary haustoria at the tip of the juvenile radicle, seen in obligate hemiparasitic species within Striga. Lastly, obligate holoparasitic behavior originated with the loss of the photosynthetic process, seen in the genus Orobanche.
To maximize resources, many parasitic plants have evolved self-incompatibility, to avoid parasitizing themselves. Others such as Triphysaria avoid parasitizing other members of their species, but some parasitic plants have no such limits; the albino redwood is a mutant Sequoia sempervirens. Parasitic plants germinate in a variety of ways; these means can either be chemical or mechanical and the means used by seeds depends on whether or not the parasites are root parasites or stem parasites. Most parasitic plants need to germinate in close proximity to their host plants because their seeds are limited in the amount of resources necessary to survive without nutrients from their host plants. Resources are limited due in part to the fact that most parasitic plants are not able to use autotrophic nutrition to establish the early stages of seeding. Root parasitic plant seeds tend to use chemical cues for germination. In order for germination to occur, seeds need to be close to their host plant. For example, the seeds of witchweed need to be within 3 to 4 millimeters of its host in order to pick up chemical signals in the soil to signal germination.
This range is important. Chemical compound cues sensed by parasitic plant seeds are from host plant root exudates that are leached in close proximity from the host’s root system into the surrounding soil; these chemical cues are a variety of compounds that are unstable and degraded in soil and are present within a radius of a few meters of the plant exuding them. Parasitic plants germinate and follow a concentration gradient of these compounds in the soil toward the host plants if close enough; these compounds are called strigolactones. Strigolactone stimulates ethylene biosynthesis in seeds causing them to germinate. There are a variety of chemical germination stimulants. Strigol was the first of the germination stimulants to be isolated, it was isolated from a non-host cotton plant and has been found in true host plants such as corn and millets. The stimulants are plant specific, examples of other germination stimulants include sorgolactone
Lycopodiopsida is a class of herbaceous vascular plants known as the clubmosses and firmosses. They have dichotomously branching stems bearing simple leaves without ligules and reproduce by means of spores borne in sporangia at the bases of the leaves. Traditionally, the group included the spikemosses and the quillworts but because these groups have leaves with ligules and reproduce using spores of two different sizes, both are now placed into another class, Isoetopsida that includes the extinct Lepidodendrales; these groups, together with the horsetails are referred to informally as fern allies. The class Lycopodiopsida as interpreted here contains a single living order, the Lycopodiales, a single extinct order, the Drepanophycales; the classification of this group has been unsettled in recent years and a consensus has yet to emerge. Older classifications took a broad definition of the genus Lycopodium that included all the species of Lycopodiales; the trend in recent years has been to define Lycopodium more narrowly and to classify the other species into several genera, an arrangement, supported by both morphological and molecular data and adopted in numerous revisions and flora treatments.
Starting from the four genera accepted by Øllgaard, a study based on chloroplast DNA produced the cladogram shown below, confirming the monophyly of the four genera, their distance from Isoetes. The genera fall into two distinct clades, but there is, as yet, no consensus as to whether to recognize them in a single family, Lycopodiaceae, or to separate them into two families: a more narrowly defined Lycopodiaceae and Huperziaceae; the family Lycopodiaceae, as narrowly defined, comprises the extant genus, which includes the wolf's-foot clubmoss, Lycopodium clavatum, ground-pine, Lycopodium obscurum, southern ground-cedar, Lycopodium digitatum, other species. Included are species of Lycopodiella, such as the bog clubmoss, Lycopodiella inundata. Most of the Lycopodium species favor acidic, upland sites, whereas most of the Lycopodiella favor acidic, boggy sites; the other major group, the family Huperziaceae, are known as the firmosses. This group includes the genus Huperzia, such as the shining firmoss, Huperzia lucidula, the rock firmoss, Huperzia porophila, the northern firmoss, Huperzia selago.
This group includes the odd, tuberous Australasian plant Phylloglossum, which was, until thought to be only remotely related to the clubmosses. However, as the cladogram above shows, it is related to the genus Huperzia; the genera Huperzia and Lycopodium are among the plants in this group with non-photosynthetic subterranean gametophytes. Lycopodium powder, the dried spores of the common clubmoss, was used in Victorian theater to produce flame-effects. A blown cloud of spores burned and brightly, but with little heat. Spikemoss, Selaginella Isoetopsida
Symbiosis is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, may be of different species. In 1879, Heinrich Anton de Bary defined it as "the living together of unlike organisms"; the term was subject to a century-long debate about whether it should denote mutualism, as in lichens. Symbiosis can be obligatory, which means that one or both of the symbionts depend on each other for survival, or facultative when they can live independently. Symbiosis is classified by physical attachment; when one organism lives on the surface of another, such as head lice on humans, it is called ectosymbiosis. The definition of symbiosis was a matter of debate for 130 years. In 1877, Albert Bernhard Frank used the term symbiosis to describe the mutualistic relationship in lichens. In 1879, the German mycologist Heinrich Anton de Bary defined it as "the living together of unlike organisms".
The definition has varied among scientists, with some advocating that it should only refer to persistent mutualisms, while others thought it should apply to all persistent biological interactions, in other words mutualisms, commensalism, or parasitism, but excluding brief interactions such as predation. Current biology and ecology textbooks use the latter "de Bary" definition, or an broader one where symbiosis means all interspecific interactions. In 1949, Edward Haskell proposed an integrative approach, proposing a classification of "co-actions" adopted by biologists as "interactions". Biological interactions can involve individuals of the same species or individuals of different species; these can be further classified by either the mechanism of the interaction or the strength and direction of their effects. Relationships can be obligate, meaning that one or both of the symbionts depend on each other for survival. For example, in lichens, which consist of fungal and photosynthetic symbionts, the fungal partners cannot live on their own.
The algal or cyanobacterial symbionts in lichens, such as Trentepohlia, can live independently, their symbiosis is, facultative. Endosymbiosis is any symbiotic relationship in which one symbiont lives within the tissues of the other, either within the cells or extracellularly. Examples include diverse microbiomes, nitrogen-fixing bacteria that live in root nodules on legume roots. Ectosymbiosis is any symbiotic relationship in which the symbiont lives on the body surface of the host, including the inner surface of the digestive tract or the ducts of exocrine glands. Examples of this include ectoparasites such as lice. Competition can be defined as an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both facilitates this type of interaction, although the competition may exist over other'amenities', such as females for reproduction. Mutualism or interspecies reciprocal altruism is a long-term relationship between individuals of different species where both individuals benefit.
Mutualistic relationships may be either obligate for both species, obligate for one but facultative for the other, or facultative for both. A large percentage of herbivores have mutualistic gut flora to help them digest plant matter, more difficult to digest than animal prey; this gut flora is made up of cellulose-digesting protozoans or bacteria living in the herbivores' intestines. Coral reefs are the result of mutualisms between coral organisms and various types of algae which live inside them. Most land plants and land ecosystems rely on mutualisms between the plants, which fix carbon from the air, mycorrhyzal fungi, which help in extracting water and minerals from the ground. An example of mutualism is the relationship between the ocellaris clownfish that dwell among the tentacles of Ritteri sea anemones; the territorial fish protects the anemone from anemone-eating fish, in turn the stinging tentacles of the anemone protect the clownfish from its predators. A special mucus on the clownfish protects it from the stinging tentacles.
A further example is a fish which sometimes lives together with a shrimp. The shrimp cleans up a burrow in the sand in which both the shrimp and the goby fish live; the shrimp is blind, leaving it vulnerable to predators when outside its burrow. In case of danger, the goby touches the shrimp with its tail to warn it; when that happens both the shrimp and goby retreat into the burrow. Different species of gobies clean up ectoparasites in other fish another kind of mutualism. A non-obligate symbiosis is seen in encru