Many dinoflagellate metabolites show very potent biological activity such as saxitoxin 19 , neosaxitoxin and gonyautoxins produced by Alexandrium and several other genera of dinoflagellates are highly selective sodium channel blockers Hall and Strichartz, On the other hand, breve-toxins 3 produced by Gymnodinium breve are potent sodium channel activators.

Another polycyclic ether, maitotoxin from Gambierdiscus toxicus , is a rare calcium channel activators Yasumoto and Maurata, A number of compounds are known to act on the signal transduction system in the cell. Kobayashi and Ishibashi reported that a symbiotic Amphidinium species from a flatworm contain a series of macrolides, amphidinolides most of them are very cytotoxic.

The structure of amphidinolide B isomers as strongly cytotoxic macrolides produced by a free-swimming dinoflagellate, Amphidinum sp. One of the compound carbenolide I 22 was extremely cytotoxic and active in vivo Bauer et al.

Many of dinoflagellate metabolites have strong antifungal activity. Goniodomin A 23 from Goniodoma Alexandrium sp. The above data proved that the probability of finding bioactive compounds from dinoflagellates is very high. Bacillariophyceae is a versatile and abundant family, which is probably the most important in the primary production in the oceans. Diatoms are fast growing and more easy to culture on a large scale. Unlike dinoflagellates, very few secondary metabolites have been reported from the diatoms Shimizu, Domic acid 25 has been isolated from Pseudonitzschia multiseries and other species; it is a harmful glutamate agonist which causes amnesic shellfish poising Wright et al.

It also produced a new type of cyclic eicosanoid bacillariolides 26 , 27 Wang and Shimizu, , Wang et al. Bacillariolide I 26 has on inhibitory activity against phospholipase A2 Shimizu, Some seaweeds have also been used as a source of additional vitamins, treatment of various intestinal disorders, as vermifuges, and as hypocholesterolaemic and hypoglycemic agents. Seaweeds have been employed as dressings, ointments and in gynecology Trease and Evanes, Macroalgae can be classified into three classes; green algae Chlorophyta , Brown algae Phaeophyta and red algae Rhodophyta Garson, The characteristic green colour of green algae is mainly due to the presence of chlorophyl a and b in the same proportion like higher plants Bold et al.

There are few reports of novel secondary metabolites among the chlorophyta than the other algal division; the following are the most important natural products isolated from these algae and their biological activities. Habu is a deadly snake inhabit in Okinawa where — people are bitten by the snake every year. A patient must be given immediate medical treatment with the serum prepared from a horse-developed antibody by injection of snake toxin. In order to develop an alternative drug, Okinawa Prefectural Institute of Public Health has been conducting screening to find out a compound with antiinflammatory activity that can be measured by suppression of the inflammation caused by the injection of the toxin on a mouse limb.

A diphenyl ether 29 isolated from an alga was found to be effective in this assay Higa, It was also active in inhibiting the growth of Escherichia coli , Bacillus subtilis and Staphylococcus aureus Kuniyoshi et al. Isorawsonol 30 has been isolated from the tropical green alga Arrainvilla rawsonii by Chen et al. The activity of IMPDH has been linked with cellular proliferation and inhibition of that enzyme has been demonstrated to have anticancer and immunosuppressive effects Chen et al.

Bioactivity-directed fractionation of the extract of the green alga Tydemania expeditionis using the protein tyrosine kinase pp60 v-stc leads to the isolation of three new cycloartenol disulfates 31 — 33 ; they showed modest inhibition of this enzyme Govindan et al. Communesins A 34 and B 35 , exhibiting cytotoxic activity against the cultured P lymphocytic leukemia cells, were isolated from the mycelium of a strain of Penicillium species stuck on the marine alga Enteromorpha intestinals Numata et al.

The compounds A—C and E exhibited a significant cytotoxicity against cultured P cell line Iwamoto et al. All the compounds exhibit significant cytotoxicity against cultured P cells Iwamoto et al. The novel compounds cytochalasans, penochalasins A B,C 45 — 47 Numata et al. All these compounds exhibited potent cytotoxic activity against cultured P cells. Halimedatrial 54 is a diterepene trialdhyde was separated from Halmida lamouroux chlorophyta, Udoteaceae species.

This compound was found to be toxic towards reef fishes, significantly reduces feeding in herbivorous fishes and has cytotoxic and antimicrobial activities Paul and Fenical, Four new diterpenoid metabolites were isolated from several species of the green algae Halimeda Udoteaceae.

These new compounds show potent antimicrobial and cytotoxic properties in bioassays. Among these 4 compounds were halimediatrial 54 and halimedalactone 55 Paul and Fenical, The cyclic depsipeptide Kahalalide F 56 was originally isolated from both mollusc Elysia rufescenes and from the dietary source, the green alga Bryopsis sp. Hamann and Scheuer, was introduced into Phase I trials by Pharma Mar as a lead compound against prostate cancer.

Green alga Bryopsis sp. Cycloeudesmol 59 is an antibiotic cycloproane containing sesquiterpene; it was isolated from the marine alga Chondria oppositiclada Dawson Fenical and Sims, Cycloeudesmol was found to be potent antibiotic against Staphylococcus aureus and Candida albicans. Lyengaroside A 60 was isolated from the green alga Codium iyengarii and displayed a moderate antibacterial activity Ali et al.

Geen algae extract of Caulerpa prolifera exhibited moderate to significant activity against unidentified strains of marine bacteria Smyrniotopoulos, From the green alga Ulva species, the endophytic and obligate marine fungus Ascochyta salicorniae was isolated. Ascochyta salicorniae was found to produce the unprecedented and structurally unusual tetramiric acid contiguous metabolites ascosalipyrrolidinones A 61 and B Ascosalipyrrolidinones A 61 has antiplasmodial activity toward Plasmodium falciarum strains Kl and NF 54, as well as showing antimicrobial activity and inhibiting tyrosine kinase pck Osterhage et al.

Halitunal 63 , is a novel diterpene aldehyde possessing a unique cyclopentadieno [ c ] pyran ring system; it has been isolated from the marine alga Halimeda tuna. Halitunal shows antiviral against murine coronavirus A59 in vitro Koehn et al.

In Garg et al. This compound was isolated from Indian green alga Ulva fasciata. Two new compounds, cymobarbatol 65 and 4-isocymobarbatol 66 were isolated from the marine green alga Cymopolia barbat. Both compounds were found to be nontoxic over a broad concentration range against Salmonella tybimurium strains T and T-lOO.

Both compounds exhibited strong inhibition of the mutagenicity of 2-aminoanthracene and ethylmethanesulphonate towards the T strains plus a metabolic activator and T Wall et al. Capisterones A 67 and B 68 are triterpene sulphate esters isolated from green alga Panicillus capitatus.

Both compounds exhibited potent antifungal activity against the marine algal pathogen Lindra thallasiae Puglisi et al. Two sesquiterpenes, caulerpals A 69 and B 70 were isolated from green alga Caulerpa taxifolia in addition to the known caulerpin Aguilar-Santos, ; they were shown to be potent inhibitor of human protein tyrosine phosphatase 1 B hPTP I B Mao et al. Capisterones A and B, originally isolated from Penicillus capitatus Garg et al.

In addition, the capisterones have been shown to significantly enhance fluconazole activity in Saccharomyces cerevisiae Li et al. A new class of ether-linked glycoglycerolipids, nigricanosides A 71 and B 72 were isolated as methyl esters from the green alga Avrainvillea nigrans.

Nigricanoside A dimethyl ester was found to be a potent antimitotic agent, acting by stimulating the polymerisation of tubulin and inhibiting the proliferation of both MCF-7 and HCT cells Williams et al.

Hydroxyisoavrainvilleol 73 was originally isolated from the tropical green alga Avrainvillea nigrican Colon et al. A vanillic acid biphenyl derivative 74 and the sulfate adduct 75 were isolated from the Australian green alga Cladophora socialis as a protein tyrosine phosphatase 1B PTPa1B inhibitors Feng et al.

Food reserves of brown algae are typically complex polysaccharides and higher alcohols. The principal carbohydrate reserve is laminarin. The cell walls are made of cellulose and alginic acid. Many bioactive metabolites have been isolated from brown algae with different pharmacological activities as shown below.

A linear cytotoxic diterpene bifurcadiol 76 was isolated from the brown alga Bifurcaria bifurcata by Guardia et al. Meroterpenoids, Sargol, Sargol-I and sargol-ll 77 — 79 were isolated from the brown alga sargassum tortile and showed a cytoxic activity Numata et al. All these compounds showed potent cytotoxicity against cultured P cells except leptosins A and C exhibited significant antitumor activity against Sarcoma ascites Takahashi et al.

Further investigation of the secondary metabolites of this fungus has led to the isolation of four additional cytotoxic compounds, named leptosins G, G1, G2 82 — 84 and H 85 Takahashi et al. Leptosins K, K1 86 — 87 and K 2 88 were also isolated and showed a potent cytotoxic activity against P cell line Takahashi et al. Leptosins I 89 and J 90 have been also isolated from the mycelium of a strain of Leptosphaeria species OUPS-4 attached to the marine alga Sargassum tortile.

These compounds exhibited significant cytotoxic activity against cultured P cells Takahashi et al. Leptosins M, MI, N and N1 91 — 94 that have been isolated from a strain of Leptsphaeria species were originally separated from the marine alga Sargassum tortile. All these compounds exhibited significant cytotoxicity against cultured P cells. Three cytotoxic diterpenes Dictyotins A, B and C 95 — 97 were isolated from brown alga Dictyota dichotoma by Wu et al. Dolabellane type of diterpene 98 have been isolated from unidentified species of Dictyota exhibit significant cytotoxicity Tringali et al.

A cytotoxic compound named as turbinaric acid 99 was isolated from Turbinaria ornate Asari et al. Four diterpene with xenicane and norxenicane — have been isolated from another species of Dityota dichotoma from Okinawa Island. In addition, showed antitumor activity. These oxygenated fucosterols exhibited cytotoxicity against various cancer cell lines Sheu et al.

Four arsenic-containing ribofuranosides — together with inorganic arsenic have been isolated from the brown alga Hizikia fusiforme which is eaten in Japan under the name hijiki Edmonds et al. Stypolactone , a diterpenoid of mixed biogenesis has been isolated from the brown algae Stypopdium zonale and showed weak cytotoxic activity in vitro against the A and H cell lines Dorta et al. Four hydroazulene diterpenes, dictyone acetate , dictyol F monoacetate , isodictytriol monoacetate and cystoseirol monoacetate were isolated from the brown alga Cystoseira myrica collected in the Gulf of Suez canal showed a moderate cytotoxicity against the murine cancer cell line KA3IT, but reduced cytotoxicity against normal NIH3T3 Ayyad et al.

Sterols B isolated from Stypopdium carpophyllum exhibited cytotoxic activity against several cultured cancer cell lines Tang et al. Two cytotoxic trihydroxylated diterpenes based on hydroxygeranylgeraniol — were isolated from brown alga Bifurcaria bifurcate Gulioli et al.

The tropical brown alga Styolpopdium zonale collected from the coast of Tenerife was the source of terpenoid C ; the methyl ester of C exhibited in vitro cytotoxic activity against HT, H and A Dorta et al.

Brown alga Perithalia capillaris yielded new bis-prenylated quinones , , both are inhibitors of superoxide production in human neutrophils in vitro and of proliferation of HL cells Blackman et al.

Jongaramru, Stypoldione was isolated from the brown alga Stypodium zonale which showed an ichthyotoxins effect. When fresh S. The fish immediately senses the toxins and attempts to jump out of the aquarium. This behavior is followed by erratic response to external stimuli, apparently difficulty in obtaining oxygen, loss of equilibrium, narcosis and eventually death.

The toxic symptoms were then proved to be due to stypoldione isolated from S. Stypoquinonic acid was isolated from the lipophilic extract of the same alga Wessels et al. Brown alga Dictyota spinulosa appeared not to be eaten by herbivores so that its constituent was examined by Tanaka and Higa and they isolated a new diterepene, hydroxydictyodial as a major component among several other related compounds.

Hydroxydictyodial has also been isolated from Dictyota crenulata Kirkup and Moore, Chemical analysis of the brown alga Notheia anomala collected from the rock platforms along the southern coast of Australia yielded cis dihydroxyte-trahydrofuran derivatives.

Tetrahydrofuran from Notheia anomala are reported for the first time as potent and selective inhibitor of the larval developments of parasitic nematodes Haemonchus contortus and Trichostrongylus colubriformis Capon et al. A meroditerpenoid has been isolated from the brown alga Cystoseira tamariscifolia and characterized as methoxybifurcarenone It possesses antifungal activity against three tomato pathogenic fungi and antibacterial activity against Agrobacterium tumefaciens and Escherichia coli Bennamara et al.

A 1,4-napthaquinone derivative deoxy lapachol , from a New Zealand brown alga Landsburgia quercifolia was isolated by the bioactivity-directed isolation method. It showed activity against P leukemic cells IC 50 0. Lobophorolide was isolated from the common brown alga Lobophora variegate and displayed a potent and highly specific activity against the marine filamentous fungi Dendroyphiella salina and Lindra thalassiae and a potent activity against C. Two new antiinflammtory macrolides, lopophorins A and B have been isolated from the fermented broths of a marine bacterium isolated from the surface of the Caribbean brown alga Lobophora variegata Dictyotales.

The new compounds are distantly related to antibiotics of Kijanimicin class and are potent inhibitors of tropical PMA-induced edema in the mouse ear assay when administered either topically or IP Jiang et al. Z -Sargaquinone , the more saturated analogue , and the known sargaquinone Ishitsuka et al.

A chlorine-containing perhydroazulene diterpene, dictyol J , was isolated from the brown alga Dictyota dichotoma along with two known diterpenes, dictyolactone Finer et al. All three metabolites were algicidal to the bloom-forming species Heterosigma akashiwo and Karenia mikimotoi. Dictyolactone also displayed a moderate activity against the dinoflagellate Alexandrium catenella.

Phloroglucinol Cross et al. A new dollabelladiene derivative and the previously isolated 10,diacetoxy — 8-hydroxy 2,6-dollabeladiene Ireland and Faulknar, were characterized from the brown alga Dictyota pfaffi Barbosa et al. The diterpenes 6 R hydroxy dichototomo 3,diene-1,dial , and the 6-acetate derivative , from the brown alga D. Dolabellane 1 , originally isolated from the opistobranch mollusc Dolabella californica Ireland and Faulknar, has been characterized as the major secondary metabolite and active chemical defence against herbivores sea urchins and fish in the brown alga Dictyota pfaffi Barbosa et al.

Several prenyl toluquinones were isolated from the brown alga Cystoseira crinita. Compounds — exhibited potent radical-scavenging effects while and were less active Fisch et al. The Brown alga Ecklonia stolonifera collected from S. Korea yielded a new phlorotannin, eckstolonol which possessed a potent DEPP radical-scavenging activity Kang et al.

The sargachromanols A—P compounds — , meroterpenoids of the chromene class, were isolated from the brown alga Sargassum siliquastrum. All the isolated compounds exhibited significant activity in the DPPH assay while compounds and were also inhibitors of butyl choline esterase Jang et al.

The known plastiquinones and were isolated from brown alga S. Compound displayed significant antioxidant activity while in contrast, was potentely active against human cytomegalo virus HCMV in vitro Iwashima et al.

Two monogalactosyl diacylglycerols and were isolated from S. Fucodiphlorethol G , a tetrameric phlorotannin, was isolated from Ecklonia cava , and was a strong radical scavenger DPPH assay Ham et al.

The known compounds taondiol Gonzalez et al. In viv o testing fucosterol which was isolated from the brown alga Pelvetia siliquosa demonstrated that it is the main antidiabetic priciciple from Pelvetia siliquosa Lee et al.

Some known phlorotannins isolated from the brown alga Ecklonia stolonifera , namely eckol Fukuyama et al. Stypopdium carpophyllum from South China Sea was the source of two new bioactive sterols A and B These sterols induced morphological abnormality in the plant pathogenic fungus Pyricularia oryzae Tang et al.

Two diterpenoids with a novel skeleton, dictyterepenoids A and B were isolated from the brown algae Dilophus okamurae displayed antifeedent activity against young abalone Suzuki et al. Most of algae form some sort of spore, which is a cell that is often motile and serves to reproduce the organism. Algae also have sex, often a very simple kind of sex where the algae themselves act as gametes, but sometimes very complicated with egg and sperm-like cells.

Giffordene is another gamete-attractant of brown algae Giffordia Hink sia mitchellae Boland et al. Two sperm-attractants of Cystophora siiiquosa and Hormosira hanksii were identified as cystophorene and hormosirene Muller et al. The walls are made of cellulose, agars and carrgeenans. Several red algae are eaten, amongst these is dulse Palmaria palmate and carrageen moss Chondrus crispus and Mastocarpus stellatus. The red algae kappaphycus and Betaphycus are now the most important sources of carrageenan, a commonly used ingredient in food, particularly yogurt, chocolate milk and prepared puddings.

Gracilaria , Gelidium , Pterocladia and other red algae are used in manufacture of the all-important agar, used widely as a growth medium for microorganisms and biotechnological applications. There are about species of red algae, most of which are of marine source.

These are found in the intertidal and in subtidal to depths of up to 40, or occasionally, m. Red algae are considered as the most important source of many biologically active metabolites in comparison to the other algal class.

Halmon is a polyhalogenated monoterpene isolated from the red alga Portieria hornemanii is considered as a novel in vitro antitumor agent by National Cancer institute NCl. Ten halogenated monoterpenes — related to the novel antitumor compound halomon or to the carbocyclic analog Fuller et al.

These results suggested that halogen at C 7 was not essential to the activity. In contrast, compound was relatively weekly cytotoxic and the minimally differential activity showed no significant correlation to that of , indicating that a halogen at C 6 was essential for the characteristic activity of — Carbocyclic compounds like and were considerably less cytotoxic than — Compound was more comparable to the overall panel-averaged potency to halomon. However, there was little differential response of the cell lines, and consequently no significant correlation to the profile of The polyhalogenated monoterpene content of six samples of the tropical marine red alga Plocamium hamatum , — collected from the southern, central and northern regions of The Great barrier Reef, Australia was assessed.

The Biological activities of compounds — and were assessed and indicated that compounds and have moderate Cytotoxic activity Koing et al. The invention of Laurinterol LOEL which was isolated from Laurencia okamurai is considered as invention for the prevention and inhibition of melanoma Moon-Moo et al.

Two new cyclic ethers consisting of squalene carbon skeleton, teurilene and thyrsiferyl acetate , have been isolated from the red alga Laurencia obtuse Suzuki et al. Thysiferyl acetate bromo ether showed remarkabaly cytotoxic property ED so of 0. Five new cytotoxic triterpenes: triterpenoids anhydrothyrsiferyl diacetate [15,didehydrodeoxythyrsiferyl] diacetate , l5-anhy-drothyrsiferyl diacetate [15,didehydro-l5-deoxy-thyrisferyl] diacetate , magireol-A , magireol B and magireol C were isolated from Japanese red alga Laurencia obtuse Suzuki et al.

Several cyclic monoterpenes — have been isolated from the Japanese red alga Desmia hornemanni , and some chemical modification have been done on these compounds to get the most active one for cytotoxic activity Higa, Compound exhibited relatively high activity against P, A lung carcinoma, and HCT-8 human colon adenocarcinoma. Okianwa red alga Laurencia yonaguniensi was the source of neoirietetraol a brominated diterpene based on the rare neoirieane skeleton was toxic to brine shrimp and was also active against marine bacteria Alcaligenes aquamarinus and E.

Furoplocamioid C , perfuroplocamioid , pirene and tetrachlorinated cyclohexane from the red alga Plocumium carttilagineum Argandona et al. Five sulfur-containing polybromoindoles — were isolated from the red alga Laurenda brongniartii , of which and were active against P cells and against HT cells El Gamal et al. The cuparene sesquiterpenes — , isolated from red alga L.

Plocaralides B and C isolated from Ploeamium species Steierle et al. Red alga Callophyeus serratus was the source of three antibacterial and antifungal diterpene-benzoate compounds, bromophycolides A and B , and a non-halogenated compound Bromophycolide A was cytotoxic against several human tumour cell lines by specific induction of apoptosis Kubanek et al. The alkaloids 2,7 naphthyridine lophocladines A and B were isolated from the red alga Lophocladia sp. Three halogenated monoterpenes — were isolated from the red alga Portiera hornemannii along with the known compound halomon Fuller et al.

Both halomon and were moderate inhibitors of DNA methyl transferase-1 Andrianasolo et al. Bromophycolides C-I — are diterpene-benzoate macrolides isolated from the red alga Callophycus serratus with modest activity against a range of human tumor cell lines Kubanek et al. The red alga Laurencia obtuse was a source of sesquiterpenes 3,7-dihydroxydihydrolaurene , perforenol B and , while L.

Compounds — were tested against five human tumour cell lines and the Chinese hamster ovary CHO cell line. Perforenol B exhibited strong activity while sesquiterpenes and exhibited weak activity. The red alga Rhodomela confervoides was the source of four bromophenols — They exhibited moderate cytotoxicity against several human cancer cell lines Ma et al.

The red alga Gracilaria asiatica was the source of three cyclopropyl derivatives, the cerebroside gracilarioside and the ceramides gracilamides A and B which were mildly cytotoxic to the human AS2 melanoma cell line Sun et al. Four somewhat air-unstable halogenated monoterpene aldehydes — were characterised from red alga Plocamium corallorhiza of which was significantly cytotoxic against an esophageal cell line Mann et al.

Three sesquiterpenes, aplysinene , epiaplysinol and debromoepiaplysinol , were isolated from red alga Laurencia tristicha. Debromo-epiaplysinol displayed selective cytotoxicity to the HeLa cell line Sun et al.

Diterpenes neorogioldiol B and prevezol B isolated from the red alga Laurencia obtusa displayed significant cytotoxicity against the human tumour cell lines MCF-7, PC3, HeLa, A and K, while prevezol C exhibited significant cytotoxicity against HeLa and A cell lines.

Prevezol D was moderately active against all cell lines IIopoulou et al. Two new polyether squalene derivatives, thyresenol A and B , have been isolated from Laurencia viridis together with the previously isolated dehydrothyrsiferol. All these compounds showed a potent cytotoxic activity against P cell lines. The marine polyether triterpenoid dehydrothyrsiferol , originally isolated from the red alga Laurencia pinnatifida was shown to induce apoptosis in esterogen-dependent and independent breast cancer cells Norte et al.

The invasive species Caulerpa racemosa was the source of know sulfoquinovosyldiacylglycerol, previously isolated from a terrestrial plant Amarquaye et al. Venustatriol , thyrsiferol and thyrsiferyl acetate were isolated from the red alga Laurencia venusta and all displayed significant antiviral activity against Vesicular stomatitis virus VSV and Herps simplex virus type 1 HSV-l Sakemi et al.

During a survey of marine organisms for anti HIV RTs activities reverse transcriptases of human immunodeficiency virus , two new sesquiterpene hydroquinone, peyssonol A and B have been isolated from the active anti HIV RTs extracts Red Sea alga Peyssonnelia species Talpir et al. Chondriamide C , a new bis indole amide and 3-indolacrylamide have been isolated from the red algae Chondria atropurpurea and showed anthelmintic activity against Nippostrongylus brasiliensis Davyt et al.

Brominated diterpenes of the parguerene and isoparguerene series were isolated from the red alga Jania rubens including the novel deoxyparguerolacetate All the isolated diterpenes had anthelmintic activity Awad, It showed weak in vitro anthelmintic activity against Nippostrongylus brasiliensis Davyt et al. Chemical investigation of the marine red alga Ceratodictyon spongiosum containing the symbiotic sponge Sigmadocia symbiotica collected from Indonesia, afforded two isomers of a new bioactive thiazole-containing cyclic heptapeptide: cis , cis- Ceratospongamide and trans , trans- ceratospongamide Tan et al.

Isolation of these peptides was assisted by bioassay-guided fractionation using a brine shrimp toxicity assay. Both compounds showed only moderate potency in the brine shrimp toxicity assay. The anti-inflammatory bromophenolic metabolites named vidalols A and B were isolated from the Caribbean red alga Vidalia obtusaloba that acts through the inhibition of phospholipase enzyme Wiemer et al.

The new compounds were discovered as part of an organized effort to isolate new naturally occurring anti-inflammatory agents with a focus upon those which may function through inhibition of phosolipase A2. Three bromophenols — and the previously reported 1,2-bis 3-bromo-4,5-dihydroxyphenyl ethane Kurata et al. Five known bromophenols, bis 2,3,6-tribromo-4,5-dihydroxyphenyl methane Wang et al.

This compound is one of the most interesting algal metabolites which is discovered by using a bioassay-directed isolation procedure Kazlauskas et al. A great example of this is Macrocystis, which is a keystone species in a giant kelp forest. As algae die, they are consumed by organisms called decomposers mostly fungi and bacteria.

The decomposers feed on decaying plants and consume the high-energy molecules essentially remineralizing the biomass into lower-energy molecules that are used by other organisms in the food web. Powered by Shopify. Menu 0. Some unexpected places where they grow are tree trunks, animal fur, snow banks, hot springs according to "Algae" and in soil, including desert crusts Current Biology, Mostly, algae live independently in their various growth forms single cells, colonies, etc.

One of the benefits of such relationships is that they enable algae to broaden the horizons of their habitats. As a general rule, algae are capable of photosynthesis and produce their own nourishment by using light energy from the sun and carbon dioxide in order to generate carbohydrates and oxygen. In other words, most algae are autotrophs or more specifically, photoautotrophs reflecting their use of light energy to generate nutrients.

However, there exist certain algal species that need to obtain their nutrition solely from outside sources; that is, they are heterotrophic. Such species apply a variety of heterotrophic strategies to acquire nutrients from organic materials carbon containing compounds such as carbohydrates, proteins and fats. Osmotrophy is the absorption of dissolved substances, and phagotrophy involves engulfing bacteria or other such prey. Other algae, known as auxotrophs, need to only acquire essential vitamins such as the B 12 complex or fatty acids according to "Algae".

According to the authors of "Algae," it is widely accepted that the nutritional strategies of algae exist on a spectrum combining photoautotrophy and heterotrophy. This ability is known as mixotrophy. Algae are capable of reproducing through asexual or vegetative methods and via sexual reproduction. According to the authors of "Algae," asexual reproduction involves the production of a motile spore, while vegetative methods include simple cell division mitosis to produce identical offspring and the fragmentation of a colony.

Sexual reproduction involves the union of gametes produced individually in each parent through meiosis. These are also referred to as blue-green algae. Though they are capable of conducting oxygen-producing photosynthesis and live in many of the same environments as eukaryotic algae, cyanobacteria are gram-negative bacteria , and therefore are prokaryotes.

They are also capable of independently conducting nitrogen fixation, the process of converting atmospheric nitrogen to usable forms of the element such as ammonia. The prefix "cyano" means blue.

These bacteria have pigments that absorb specific wavelengths of light and give them their characteristic colors. Many cyanobacteria have the blue pigment phycocyanin, a light-harvesting pigment it absorbs red wavelengths of light.

Cyanobacteria all have some form of the green pigment chlorophyll, which is responsible for harvesting light energy during the photosynthetic process Current Biology, Some others also have the red pigment phycoerythrin, which absorbs light with the green region and bestows the bacteria with a pink or red color.

The eukaryotic algae are polyphyletic , meaning that they did not evolve from a single common ancestor. This is clearly demonstrated in our current understanding of the tree of life — a family tree of all living organisms organized by their various evolutionary relationships.

Eukaryotic algae are found distributed among many different groups, or major branches of the tree. Archaeplastida includes plants and a variety of photosynthetic algal species such as the chlorophytes a subset of green algae , charophytes mainly freshwater green algae and glaucocystophytes unicellular freshwater algae.