Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates, foraminiferans, radiolarians, some dinoflagellates and marine microanimals. Macroscopic zooplankton (not covered further here) include pelagic cnidarians , ctenophores , molluscs , arthropods and tunicates , as well as planktonic arrow worms and bristle worms .https://en.wikipedia.org/wiki/Marine_microbial
Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Life originated as single-celled prokaryotes (bacteria and archaea) and later evolved into more complex eukaryotes .
Marine life, or sea life or ocean life, is the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms, mostly microorganisms, produce oxygen and sequester carbon. Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land. The term marine comes from the Latin mare, meaning sea or ocean
Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates, foraminiferans, radiolarians, some dinoflagellates and marine microanimals. Macroscopic zooplankton (not covered further here) include pelagic cnidarians , ctenophores , molluscs , arthropods and tunicates , as well as planktonic arrow worms and bristle worms .
Marine protists are defined by their habitat as protists that live in marine environments, that is, in the saltwater of seas or oceans or the brackish water of coastal estuaries. Protists are eukaryotes that cannot be classified as plants, fungi or animals. They are usually single-celled and microscopic. Life originated as single-celled prokaryotes (bacteria and archaea) and later evolved into ...
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Marine life, or sea life or ocean life, is the plants, animals and other organisms that live in the salt water of the sea or ocean, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. Marine organisms, mostly microorganisms, produce oxygen and sequester carbon. Shorelines are in part shaped and protected by marine life, and some marine organisms even help create new land.
- Archaeal Viruses
- Fungal Viruses
- Eukaryote Viruses
- Giant Marine Viruses
- Role of Marine Viruses
- Marine Habitats
- See Also
Viruses are now recognised as ancient and as having origins that pre-date the divergence of life into the three domains. They are found wherever there is life and have probably existed since living cells first evolved. The origins of viruses in the evolutionary history of life are unclear because they do not form fossils. Molecular techniques are used to compare the DNA or RNA of viruses and are a useful means of investigating how they arose. Some viruses may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria. In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity. Opinions differ on whether viruses are a form of life or organic structures that interact with living organisms. They are considered by some to be a life form, because they carry genetic material, reproduce by creating multiple copies of themselves through self-assembly, and evolve through natural selection....
Bacteriophages, often just called phages, are viruses that parasite bacteria. Marine phages parasite marine bacteria such as cyanobacteria. They are a diverse group of viruses which are the most abundant biological entity in marine environments, because their hosts, bacteria, are typically the numerically dominant cellular life in the sea. There are up to ten times more phages in the oceans than there are bacteria, reaching levels of 250 million bacteriophages per millilitre of seawater. These viruses infect specific bacteria by binding to surface receptor molecules and then entering the cell. Within a short amount of time, in some cases just minutes, bacterial polymerasestarts translating viral mRNA into protein. These proteins go on to become either new virions within the cell, helper proteins, which help assembly of new virions, or proteins involved in cell lysis. Viral enzymes aid in the breakdown of the cell membrane, and there are phages that can replicate three hundred phages...
Archaean viruses replicate within archaea: these are double-stranded DNA viruses with unusual and sometimes unique shapes. These viruses have been studied in most detail in the thermophilic archaea, particularly the orders Sulfolobales and Thermoproteales. Defences against these viruses involve RNA interference from repetitive DNA sequences within archaean genomes that are related to the genes of the viruses.Most archaea have CRISPR–Cas systems as an adaptive defence against viruses. These enable archaea to retain sections of viral DNA, which are then used to target and eliminate subsequent infections by the virus using a process similar to RNA interference.
Mycoviruses, also known as mycophages, are viruses that infect fungi. The infection of fungal cells is different from that of animal cells. Fungi have a rigid cell wall made of chitin, so most viruses can get inside these cells only after trauma to the cell wall. 1. See; Nerva, L.; Ciuffo, M.; Vallino, M.; Margaria, P.; Varese, G.C.; Gnavi, G.; Turina, M. (2016). "Multiple approaches for the detection and characterization of viral and plasmid symbionts from a collection of marine fungi". Virus Research. 219: 22–38. doi:10.1016/j.virusres.2015.10.028. hdl:2318/1527617. PMID 26546154.
By 2015, about 40 viruses affecting marine protists had been isolated and examined, most of them viruses of microalgae. The genomes of these marine protist viruses are highly diverse. Marine algae can be infected by viruses in the family Phycodnaviridae. These are large (100–560 kb) double-stranded DNA viruses with icosahedral shaped capsids. By 2014, 33 species divided into six genera had been identified within the family, which belongs to a super-group of large viruses known as nucleocytopl...
Marine invertebrates are susceptible to viral diseases. Sea star wasting disease is a disease of starfish and several other echinoderms that appears sporadically, causing mass mortality of those affected. There are around 40 different species of sea stars that have been affected by this disease. In 2014 it was suggested that the disease is associated with a single-stranded DNA virus now known as the sea star-associated densovirus(SSaDV); however, sea star wasting disease is not fully understood.
Fish are particularly prone to infections with rhabdoviruses, which are distinct from, but related to rabies virus. At least nine types of rhabdovirus cause economically important diseases in species including salmon, pike, perch, sea bass, carp and cod. The symptoms include anaemia, bleeding, lethargy and a mortality rate that is affected by the temperature of the water. In hatcheries the diseases are often controlled by increasing the temperature to 15–18 °C.:442–443 Like all vertebrates, f...
Most viruses range in length from about 20 to 300 nanometers. This can be contrasted with the length of bacteria, which starts at about 400 nanometers. There are also giant viruses, often called giruses, typically about 1000 nanometers (one micron) in length. All giant viruses belong to the phylum Nucleocytoviricota (NCLDV), together with poxviruses.The largest known of these is Tupanvirus. This genus of giant virus was discovered in 2018 in the deep ocean as well as a soda lake, and can reach up to 2.3 microns in total length. 1. The giant mimivirus 2. Cryo-electron micrograph of the CroV giant virus scale bar=0.2µm The discovery and subsequent characterization of giant viruses has triggered some debate concerning their evolutionary origins. The two main hypotheses for their origin are that either they evolved from small viruses, picking up DNA from host organisms, or that they evolved from very complicated organisms into the current form which is not self-sufficient for reproducti...
Virophages are small, double-stranded DNA viruses that rely on the co-infection of giant viruses. Virophages rely on the viral replication factory of the co-infecting giant virus for their own replication. One of the characteristics of virophages is that they have a parasitic relationship with the co-infecting virus. Their dependence upon the giant virus for replication often results in the deactivation of the giant viruses. The virophage may improve the recovery and survival of the host organism. Unlike other satellite viruses, virophages have a parasiticeffect on their co-infecting virus. Virophages have been observed to render a giant virus inactive and thereby improve the condition of the host organism. All known virophages are grouped into the family Lavidaviridae (from "large virus dependent or associated" + -viridae). The first virophage was discovered in a cooling tower in Paris, France in 2008. It was discovered with its co-infecting giant virus, Acanthamoeba castellanii ma...
Although marine viruses have only recently been studied extensively, they are already known to hold critical roles in many ecosystem functions and cycles. Marine viruses offer a number of important ecosystem services and are essential to the regulation of marine ecosystems. Marine bacteriophages and other viruses appear to influence biogeochemical cycles globally, provide and regulate microbial biodiversity, cycle carbon through marine food webs, and are essential in preventing bacterial population explosions.
Along the coast
Marine coastal habitats sit at the interface between the land and the ocean. It is likely that RNA virusesplay significant roles in these environments.
At the ocean surface
Marine surface habitats sit at the interface between the atmosphere and the ocean. The biofilm-like habitat at the surface of the ocean harbours surface-dwelling microorganisms, commonly referred to as neuston. Viruses in the microlayer, the so-called virioneuston, have recently become of interest to researchers as enigmatic biological entities in the boundary surface layers with potentially important ecological impacts. Given this vast air–water interface sits at the intersection of major ai...
In the water column
Marine viral activity presents a potential explanation of the paradox of the plankton proposed by George Hutchinson in 1961. The paradox of the plankton is that many plankton species have been identified in small regions in the ocean where limited resources should create competitive exclusion, limiting the number of coexisting species. Marine viruses could play a role in this effect, as viral infection increases as potential contact with hosts increases.Viruses could therefore control the pop...
Pages in category "Marine organisms" The following 15 pages are in this category, out of 15 total. This list may not reflect recent changes ().
- Marine plants
Marine fungi are species of fungi that live in marine or estuarine environments. They are not a taxonomic group, but share a common habitat. Obligate marine fungi grow exclusively in the marine habitat while wholly or sporadically submerged in sea water. Facultative marine fungi normally occupy terrestrial or freshwater habitats, but are capable of living or even sporulating in a marine habitat. About 444 species of marine fungi have been described, including seven genera and ten species of basi
Terrestrial fungi play critical roles in nutrient cycling and food webs and can shape macroorganism communities as parasites and mutualists. Although estimates for the number of fungal species on the planet range from 1.5 to over 5 million, likely fewer than 10% of fungi have been identified so far. To date, a relatively small percentage of described species are associated with marine environments, with ∼1,100 species retrieved exclusively from the marine environment. Nevertheless, fungi ...
In contrast to plants and animals, the early fossil record of the fungi is meager. Since fungi do not biomineralise, they do not readily enter the fossil record. Fungal fossils are difficult to distinguish from those of other microbes, and are most easily identified when they resemble extant fungi.
The greatest number of known species of marine fungi are from mangrove swamps. In one study, blocks of mangrove wood and pieces of driftwood of Avicennia alba, Bruguiera cylindrica and Rhizophora apiculata were examined to identify the lignicolous fungi they hosted. Also tested w
The sea snail Littoraria irrorata damages plants of Spartina in the coastal sea marshes where it lives, which enables spores of intertidal ascomycetous fungi to colonise the plant. The snail eats the fungal growth in preference to the grass itself. This mutualism between the snai
Many marine fungi are very specific as to which species of floating and submerged wood they colonise. A range of species of fungi colonise beech while oak supports a different community. When a fungal propagule lands on a suitable piece of wood, it will grow if no other fungi are present. If the wood is already colonised by another fungal species, growth will depend on whether that fungus produces antifungal chemicals and whether the new arrival can resist them. The chemical properties of coloni
Lichens are mutualistic associations between fungi, usually an ascomycete with a basidiomycete, and an alga or a cyanobacterium. Several lichens, including Arthopyrenia halodytes, Pharcidia laminariicola, Pharcidia rhachiana and Turgidosculum ulvae, are found in marine environments. Many more occur in the splash zone, where they occupy different vertical zones depending on how tolerant they are to submersion. Lichen-like fossils have been found in the Doushantuo Formation in China dating back ab
Human activities affect marine life and marine habitats through overfishing, habitat loss, the introduction of invasive species, ocean pollution, ocean acidification and ocean warming. These impact marine ecosystems and food webs and may result in consequences as yet unrecognised for the biodiversity and continuation of marine life forms.