INTRODUCTION TO THE LIVING WORLD KINGDOM MONERA KINGDOM PROTISTA LECT # 2.

INTRODUCTION TO THE LIVING WORLD KINGDOM MONERAKINGDOM PROTISTA

LECT # 2

FILAMENTOUS ALGAE• While the colonial body form appears to be a dead end from an

evolutionary viewpoint, the filamentous algae apparently had the morphological flexibility to develop into more complex aquatic and terrestrial plants. The simplest filamentous algae consist of a thallus (body) of a single chain of cells. This is the result of cell division in one plane only. Branching filaments occur when there is periodic division in a second plane Once this stage of development was reached, the next step was to evolve more complex branching patterns. Some cells in the filaments divide several times in different planes resulting in thick and thin portions. Finally, some filamentous algae began to show some cellular differentiation. For example, thin portions penetrate the substrate, thicker portions lie on the surface, and erect portions of the thallus project about the mass and bear reproductive structures. This could easily lead to a division of labour among the three areas. The algae that evolved these features were ones that attached to the substrate or lived on damp soils

FILAMENTOUS ALGAE

Anabaena• is a genus of filamentous

cyanobacteria that exists as plankton. It is known for its nitrogen fixing abilities, and they form symbiotic relationships with certain plants, They are one of four genera of cyanobacteria that produce neurotoxins which are harmful to local wildlife, as well as farm animals and pets

FILAMENTOUS ALGAE

Nostoc• filaments are made up of spherical or

barrel-shaped cells of uniform size that are blue-green or olive green in color. The bent, kinked, or coiled filaments are long, isopolar, and held together by firm mucilage. The colonies may be microscopic or macroscopic, smooth or warty in texture, loose or dense, and spherical, flat, gelatinous, or in irregular mats. Spherical colonies are usually marble-sized, but may be as large as 30-50 cm in diameter. The mucilaginous sheaths are firm and wide, yellow, brown, or black in color, and are most easily viewed in young colonies.

FILAMENTOUS ALGAE

NostocThe heterocysts (arrow, top right image) are solitary, barrel-shaped or spherical, and may be intercalary or located at the ends of the trichomes. The akinetes are ellipsoidal and only slightly larger than the vegetative cells. The akinetes of Nostoc are usually located halfway between the heterocysts. This differs from Anabaena, where the akinetes are normally adjacent to the heterocysts.

FILAMENTOUS ALGAE

Zygnema• is a very common alga and is usually found along

side Spirogyra in quite still waters. Zygnema can be instantly recognised by the two stellate chloroplasts that are embedded in each filament. The very dark regions in the above photograph are probably where the pyrenoids are located. There are many species of Zygnema and it is very difficult to establish which species that you have, G.W.Prescott in his book (How to know the freshwater algae) states that species can be identified by the zygospores that they produce, being round, oval etc. When viewed in the water the filaments look a yellow - green colour, and like Spirogyra are slimy to the touch. I have been unable to observe the reproduction of this alga because it does not appear to occur quite has frequently as in Spirogyra. I am hoping to get further samples so I can make more observations this spring

FILAMENTOUS ALGAE

Oscillatoria• This genus is named for the

gliding, rotating, or oscillating motion of the filament around its axis. The trichomes are straight, slightly undulating, or coiled, and are made up of disk-shaped cells wider than they are long. In some species the end cells can be rounded or tapered. The cells do not have gas vesicles, but sometimes contain large granules

FILAMENTOUS ALGAE

Oscillatoria

• Oscillatoria does not usually have a true sheath, although parallel filaments may form a thin film. Mucilage sheaths may also occasionally form under stressful conditions, such as dessication or hypersalinity, or in culture.

FILAMENTOUS ALGAE

Rivularia• Filaments heteropolar, differentiated into basal and

apical parts, simple, joined parallely into firm, at the beginning of the vegetation cycle hemispherical or spherical, later sometimes vaste, flat, macroscopic, irregular strata, up to several cm or dm in diameter and several mm thick; strata are layered (sometimes with several layers), with densely agglomerated trichomes, oriented by their bases with heterocytes to the substrate and by the apical hair-like parts to the surface ofthe colony. Strata are gelatinous up to leathery or intensely incrusted by calcium carbonate, always covering the substrate. Trichomes +/- cylindrical, constricted or unconstricted at the cross walls, dividing at intercalar heterocytes: the divided trichomes separate one from another, but remain parallely located within the mother sheaths in the colony. Hairs are composed from the narrow, long, hyaline cells. Sheaths firm, sometimes lamellated, colourless or yellow-brown, enveloping all the "daughter" trichomes, which produce their own

FILAMENTOUS ALGAE

Scytonema • filaments form dark mats or tufts amongst

other algae or submerged vegetation in lakes or on terrestrial stones, wood, or soil. The trichomes are cylindrical and isopolar, and are usually colored pale blue-green, olive green, brownish, or even violet. The apical ends of the filaments are not tapered, but the end cells may slightly rounded or widened. The cells sometimes have constricted cross walls and contain groups of long, cylindrical gas vesicles. The heterocysts are located throughout the filaments and are rectangular and solitary, with darkly-pigmented cell walls. The trichomes are contained within mucilage that is commonly tough, wide, sometimes layered, and may be colored brown, yellow, or orange.

FILAMENTOUS ALGAE

Scytonema• Double false branching often

forms when a filament breaks apart at the site of a dead cell. Both ends of the filament then break through the mucilage sheath and continue to grow as "branches". Occasionally, false branching also forms at a heterocyst where the filament breaks apart in a similar manner

FILAMENTOUS ALGAE

Stigonema• Filamentous - thallous; thallus wooly

or crusty, composed from free, coiled, true branched filaments, usually attached to the substrate, not diversified distinctly in basal filaments and branches. Trichomes two or multiseriate (only in young trichomes and at ends of branches uniseriate), sometimes very thick, irregularly laterally true branched (T- and V-type of branching), irregularly coiled, sometimes narrowed (with less number of cell rows) towards the ends, apical cell is

PARENCHYMATOUS ALGAE

Enteromorpha• The thallus of Enteromorpha is tubular with

the wall of the tube a single cell layer thick. The thallus can be branched or unbranched, and there is a wide variety of forms within the genus. Enteromorpha is attached to the substrate by a disc-like holdfast. The holdfast is formed by the basal cell dividing into three or four holdfast cells which elongate and undergo further division.

• The cells in Enteromorpha can vary in size and shape from species to species, and sometimes they will form regular linear series in a frond, while other times there is an irregular arrangement of the cells. Each cell contains a single chloroplast, varying in size depending on the size of the cell.

PARENCHYMATOUS ALGAE

Ulva• genus of algae that includes species that look

like bright green sheets and live primarily in marine environments. They can also be found in brackish water, particularly estuaries. They live attached to rocks in the middle to low intertidal zone, and as deep as 10 meters in calm, protected harbors. Ulva are usually seen in dense groups. Commonly known as the sea lettuce or the green laver, Ulva species can be eaten in soups and salads, and used as a substitute for nori (Porphyra the popular seaweed in sushi. Ten species of Ulva exist worldwide, all of which have representation on the coast of California. The shapes of Ulva are quite varied- circular to oval to long and narrow, ranging in size from microscopic to 65 cm. They have fine, silky textures with waved or ruffled margins. The delicate blades of Ulva are usually only 40 microns thick.

SIPHONOUS ALGAE

Vaucheria• Genus of yellow-green algae characterized

by multinucleate tubular branches lacking cross walls except in association with reproductive organs or an injury. Food is stored as oil globules. Asexual reproduction is by motile multiflagellate zoospores and nonmotile aplanospores; sexual reproduction also occurs. The spherical female sex organ (oogonium) and the slender hook-shaped male sex organ (antheridium) are usually produced on branches close to each other. After the nonmotile egg is fertilized by a biflagellate sperm, the zygote may enter a resting phase for several weeks before germinating into a new plant. Most species occur in fresh water and some are marine.

SIPHONOUS ALGAEVaucheria

• has siphonaceous, coenocytic filaments that can form feltlike mats, earning it the nickname "water felt". Cytokinesis does not usually follow mitosis, so the cells retain multiple nuclei. The thallus has cross walls only where gametes or zoospores were produced, and may be branched. The cytoplasm of Vaucheria is pushed to the cell periphery by large vacuoles, and contains many nuclei and discoid plastids. The plastids can change their orientation in response to changes in light levels. The large cells rely on cytoplasmic streaming to move materials around as needed

GIANT ALGAE

Sargassum• is a genus of brown (class Phaeophyceae)

macroalga (seaweed) in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral reefs. However, the genus may be best known for its planktonic (free-floating) species. Any number of the normally benthic species may take on a planktonic, often pelagic existence after being removed from reefs during rough weather. However, two species (S. natans and S. fluitans) have become holopelagic — reproducing vegetatively and never attaching to the seafloor during their lifecycle

REFERENCES • http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-u

k.org.uk/mag/artdec03/volvox.html• http://www.algaebase.org/search/species/detail/?species_id=27511• http://www.cyanodb.cz/Stigonema• http://books.google.com/books?

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