noun
definition
Any of many aquatic photosynthetic organisms, including the seaweeds, whose size ranges from a single cell to giant kelps and whose biochemistry and forms are very diverse, some being eukaryotic.
noun
definition
Algal organisms viewed collectively or as a mass; algal growth.
definition
A particular kind of algae.
Examples of algae in a Sentence
In both Algae and Fungi the latter are primarily supporting and food-conducting, and in.
Several of the marine and many species of freshwater algae are peculiar to the island.
Secondly, in the Algae, which build up their own food from inorganic materials, we have a differentiation.
Among the Green Algae the differentiation of cells is comparatively slight.
The algal fungi, Phycomycetes, are obviously derived from the Green Algae, while the remaining Fungi, the Eumycetes, appear to have sprung from the same stock as the Rhodophyceae.
Thus all existing hygrophytes (excepting the Algae) are considered to have been derived from land-plants which have adapted themselves to a watery habitat.
The surface-layer of the body in the massive Fungi differs in character according, to its function, which is not constant throughout the class, as in the Algae, because of the very various conditions of life to which different Fungi are exposed.
Certain Algae have been found capable of forming nutritive carbohydrates in darkness, when supplied with a compound of this body with sodium-hydrogen-sulphite.
Palaeontological evidence conclusively proves that the surface of the earth has been successively occupied by vegetative forms of increasing complexity, rising from the simplest algae to the most highly organized flowering plant.
There is considerable difficulty in removing mounted specimens of algae from paper, and therefore a small portion preserved on mica should accompany each specimen, enclosed for safety in a small envelope fastened at one corner of the sheet of paper.
For the carrying on of their functions they all need to be supplied with carbohydrates or other carbon compounds which they obtain ordinarily from humus and plant residues in the soil, or possibly in some instances from carbohydrates manufactured by minute green algae with which they live in close union.
Green algae can appear in several forms.
Similar modes of growth occur among the Siphoneous Green Algae and also among the Red Seaweeds.
The culture of such algae may prove of economic importance; gelatine, glue and agar-agar would be valuable by-products.
From the primitive uniform Systems. mass of undifferentiated assimilating cells, which we may conceive of as the starting-point of differentiation, though such an undifferentiated body is only actually realized in the thallus of the lower Algae, there is, (1) on the one hand, a specialization of a surface layer regulating the immediate relations of the plant with its surroundings.
Many of the freshwater algae which form a mere crust, such as Palmella cruenta, may be placed in a vessel of water, where after a time they float like a scum, the earthy matter settling down to the bottom, and may then be mounted by slipping a piece of mica under them and allowing it to dry.
In 1865 De Bary suggested the possibility that such lichens as Collema, Ephebe, &c., arose as a result of the attack of parasitic Ascomycetes upon the algae, Nostoc, Chroococcus, &c. In 1867 the observations of Famintzin and Baranetzky showed that the gonidia, in certain cases, were able to live outside the lichen-thallus, and in the case of Physcia, Evernia and Cladonia were able to form zoospores.
The most common type of alga that grows in swimming pools is called green algae.
The thallus in all cases consists of a branched filament of cells placed end to end, as in many of the Green Algae.
It is generally admitted that life originated in water, and that the earliest plants were Algae.
At low tide the limpet (being a strictly intertidal organism) is exposed to the air, and (according to trustworthy observers) quits its attachment and walks away in search of food (minute encrusting algae), and then once more returns to the identical spot, not an inch in diameter, which belongs, as it were, to it.
Waves and tidal currents produce their full effects in that region, and in high latitudes the effect of transport of materials by ice is very important; while in the warm water of the tropics the reefbuilding animals and plants (corals and calcareous algae) carry on their work most effectively there.
In cannel coals the prevailing constituents are the spores of cryptogamic plants, algae being rare or in many cases absent.
The fungal part of the organism nearly always consists of a number of the Discomycetes or Pyrenomycetes, while the algal portion is a member of the Schizophyceae (Cyanophyceae or Blue-green Algae) or of the Green Algae; only in a very few cases is the fungus a member of the Basidiomycetes.
Baranetzky therefore concluded that a certain number, if not all of the so-called algae were nothing more than free living lichen-gonidia.
In 1869 Schwendener put forward the really illuminating view - exactly opposite to that of Baranetzkythat the gonidia in all cases were algae which had been attacked by parasitic fungi.
Although Schwendener supported this view of the " dual " nature of lichens by very strong evidence and identified the more common lichen-gonidia with known free-living algae, yet the theory was received with a storm of opposition by nearly all lichenologists.
Funf stuck gives ten free living algae which have been identified as the gonidia of lichens.
They are distinguished by possessing as gonidia algae foreign to the ordinary part of the thallus.
In the whole parts known among Green Algae.
The foreign algae are always members of the Cyanophyceae and on the same individual and even in the same cephalodium more than one type of gonidium may be found.
In many other cases, especially those algae possessing Pleurococcus as their gonidia, there are no penetrating hyphae, but merely From Strasburger's Lehrbuck der Botanik, by permission of Gustav Fischer.
As is clear from the above, nearly all the lichens are produced by the association of an ascomycetous fungus with algae.
Clavaria mucida, however, h a s apparently some claims to be considered as a Basidiolichen, since the base of the fruit body and the thallus from which it arises, according to Coker, always shows a mixture of hyphae and algae.
The lichen algae are not alone in their specializa tion to the symbiotic (or parasitic) mode of life, for, as stated earlier, the fungus appear in the majority of cases to have completely lost the power of independent development since with very rare exceptions they are not found alone.
The water which trickles over the rims of the pools and basins on the upper terraces is a transparent blue, while the formation itself contains a network of fibrous algae which gives it a wonderful variety of colours.
Algae and fungi also were present, but there were no flowering plants.
On the other hand, lichens, previously regarded as autonomous plants, are now known to be dual organisms - fungi symbiotic with algae.
The real difficulty of classification of the fungi lies in the polyphyletic nature of the group. There is very little doubt that the primitive fungi have been derived by degradation from the lower algae.
It is also possible in the absence of satisfactory intermediate forms that the Ascomycetes and Basidiomycetes have also been derived from the algae independently of the Phycomycetes, and perhaps of one another.
The resemblance between this genus and Oedogonium among the algae is very striking, as is also that of Myrioblepharis and Vaucheria.
They are usually included in Oomycetes, but their simple structure, minute size, usually uniciliate zoospores, and their negative characters would justify their retention as a separate group. It contains less than 200 species, chiefly parasitic on or in algae and other water-plants or animals, of various kinds, or in other fungi, seedlings, pollen and higher plants.
Analogies have been pointed out between Chytridiaceae and unicellular algae, such as Chlorosphaeraceae, Protococcaceae, "Palmellaceae," &c., some of which are parasitic, and suggestions may be entertained as to possible origin from such algae.
In this point and in their method of fertilization theLaboulbeniineae suggest a possible relationship of Ascomycetes and the Red Algae.
Without this occasional drying of the soil the finer grasses and the leguminous plants will infallibly be lost; while a scum of confervae and other algae will collect upon the surface and choke the higher forms of vegetation.
Of the fifteen genera included by Linnaeus among algae, not more than six - viz.
The excluded genera are distributed among the liverworts, lichens and fungi; but notwithstanding the great advance in knowledge since the time of Linnaeus, the difficulty of deciding what limits to assign to the group to be designated Algae still remains.
It arises from the fact that algae, as generally understood, do not constitute a homogeneous group, suggesting a descent from a common stock.
Among them there exist, as will be seen hereafter, many well-marked but isolated natural groups, and their inclusion in the larger group is generally felt to be a matter of convenience rather than the expression of a belief in their close inter-relationship. Efforts are therefore continually being made by successive writers to exclude certain outlying sub-groups, and to reserve the term Algae for a central group reconstituted on a more natural basis within narrower limits.
It is perhaps desirable, in an article like this, to treat of algae in the widest possible sense in which the term may be used, an indication being at the same time given of the narrower senses in which it has been proposed to employ it.