Classification of algae By Fritsch is one of the famous and accepted classifications in algology. F.E Fritsch classified algae and published it in his book, The Structure and Reproduction of the Algae. He classified algae into 11 classes. His classification of algae was based on characteristics such as,
- Pigmentation
- Types of flagella
- Thallus structure
- Assimilatory products
- Modes of reproduction.
Classification Of Algae By Fritsch
- Chlorophyceae
- Xanthophyceae
- Chrysophyceae
- Bacillariophyceae
- Cryptophyceae
- Dinophyceae
- Chloromonadineae
- Euglenineae
- Phaeophyceae
- Rhodophyceae
- Myxophyceae(Blue-green algae)
Fritsch’s Classification of Algae and Their Characteristics
Myxophyceae (Cyanophyceae)
Simple plants with no nucleus and chromatophores. The presence of phycocyanin gives them a blue-green color. Phycobilisomes are present as accessory pigments. Chlorophyll is present in the thylakoids. Protein granules and myxophycean starch are the reserve food materials in them. Sexual reproduction is absent in these algae.
Fritsch assigned 5 orders under Myxophyceae.
- Chroococcales (Gleocapsa, Microcystis)
- Chamaesiphonales (Chamesiphon, Dermocarpa)
- Pleurocapsales (Pleurocapsa)
- Nostocales (Nostoc, Oscillatoria, Anabaena, Gloeotrichia, Rivularia, Scytonema,
- Spirulina)
- Stigonematales (Nostochopsis, Stigonema, Mastigocladium)
Euglenophyceae
Unicellular flagellates have characters of plants and animals. They exist as solitary plants or colonial while some are attached. Possess a nucleus, vacuole, chloroplasts, and an eyespot. Their naked and ciliated reproductive organs make them resemble microscopic animal structures. e.g. Euglena, Heteronema, etc.
Chlorophyceae
Plants vary in structure and number of flagella. Mainly have freshwater chlorophyllous thallus. The cell wall is made of cellulose and the reserve material is starch. Motile cells having cilia are characteristics of algae in this group. Sexual reproduction can be oogamous, isogamous, or anisogamous.
According to the classification of algae by Fritsch, Chlorophyceae is divided into 9 orders.
- Volvocales (Volvox)
- Chlorococcales (Chlorella)
- Ulothrichales (Ulothrix)
- Cladophorales (Cladophora)
- Chaetophorales (Fritschiella)
- Oedogoniales (Oedogonium)
- Conjugales (Zygnema)
- Siphonales (Vaucheria)
- Charales (Chara)
Chloromonadineae
Algae in this group are bright or olive-green in color. They have abundant amounts of xanthophyll. Several discoid chloroplasts are present. They reproduce by longitudinal division. Chloromonadinae has only one order- Chloromonadales (Vacuolaria, Trentonia)
Xanthophyceae (Heterokontae)
Due to the presence of xanthophylls, algae in this group appear yellow or green-yellow. They lack pyrenoids and the reserve food material is fat. Unequal flagella and cell walls of equal or unequal length overlap.
Fritsch assigned 4 orders under the class Xanthophyceae.
- Heterochloridales (Heterochloris, Chloramoeba)
- Heterococcales (Myxochloris)
- Heterotrichales(Tribonema)
- Heterosiphonales (Botrydium)
Chrysophyceae
Algae in this group contain chlorophyll, yellow-green pigments, phycochrysin, and phycocyanin. Phycochrysin is a pigment that imparts the characteristic yellow or orangish color. The plants are in colonial forms of unicellular or multicellular algae. Cell walls may or may not be present. When present, it is seen as overlapped halved. Algae has silicified cysts, and 1-3 flagella. The reserve food material is leuosin.
As per the classification of algae by Fritsch, Chrysophyceae consists of 3 orders.
- Chrysomonadales (Chrysodendron)
- Chrysosphaerales (Chrysosphaera)
- Chrysotrichales (Chrysoclonium)
Bacillariophyceae (Diatoms)
Algae here are yellow-green or olive-green in appearance. Chloroplast contains diatomin. Pyrenoids are commonly seen. The habits are unicellular and non-motile. The cell wall is silicified and contains pectose. They are symmetrical in appearance with delicate markings on them.
Bacillariophyceae consists of just 2 orders.
- Centrales (Cyclotella, Chaetoceras)
- Pennales (Grammatophora , Navicula)
Cryptophyceae
Algae appear, green, red, greenish-blue, or olive-green. They are mainly seen in freshwater but also in marine habitats. Each cell with 2 two large parietal chloroplasts, two unequal flagella, and cysts present and endogenous.
Cryptophyceae has only two orders.
- Crptomonadales (Cryptomonas, Chilomonas)
- Cryptococcales (Tetragonidium)
Dinophyceae (Peridineae)
Algae appear, red, brown, or dark yellow. Unicellular, motile, filamentous, longitudinal and transverse furrow, large nucleus and discoid chromatophores, cell wall sculptured, biflagellate. The reserve material is oil or starch. Eg. Heterocapsa, Ceratium, Peridinium, etc.
Dinophyceae has 6 orders assigned by Fritsch.
- Desmomonadales (Desmocapsa)
- Dinophysales (Dinophysis)
- Thecatales (Exuviaella)
- Dinoflagellata (Ceratium)
- Dinococcales (Cystodinium)
- Dinotrichales (Dinothrix)
Phaeophyceae
Plants appear yellow or brown-colored. The main coloring pigment is fucoxanthin. Their reserve food material is mannitol, fats, or laminarin. Filamentous or organized seaweeds, flagella on both sides- one for forward and the other for backward movement, produce uni, or plurilocular sporangia. Zoospores are biciliated with unequal ones. The zygote does not undergo any resting period.
Phaeophyceae has 9 orders under the classification of algae by Fritsch.
- Ectocarpales (Ectocarpus)
- Tilopteridales (Tilopteris)
- Cutleriales (Cutleria)
- Sporochnales (Sporochnus)
- Desmarestiales (Desmarestia)
- Laminariales (Laminaria, Macrocystis)
- Sphacelariales (Sphacelaria, Haploteris)
- Dictyotales (Dictyota)
- Fucales (Fucus, Sargassum)
Rhodophyceae
These are marine algae having phycoerythrin pigment giving them a red color. The reserve food material here is floridean starch. Filamentous or highly organized body, protoplasmic connections between cells, cystocarps produce carpospores that germinate to form tetrasporic diploid plants.
Under the classification of algae by Fritsch, Rhodophyceae has 7 orders under it.
- Bangiales (Bangia, Porphyra, Porphyridium)
- Nemalionales (Batrachospermum, Nemalion)
- Gelidiales ( Gelidium)
- Cryptonemiales (Corallina)
- Gigartinales (Gigartina, Gracilaria )
- Rhodymeniales ( Champia, Rhodymenia)
- Ceramiales ( Ceramium, Polysiphonia)
| Class | Occurrence | Pigments | Reserve food | Structure | Reproduction |
| Chlorophyceae | Mostly freshwater some marine | Chl a, Chl b, carotenoids | Starch | Unicellular motile, heterotrichous branched | Isogamous to oogamous. |
| Xanthophyceae | Mostly freshwater, some marine | Yellow xanthophylls | Oil | Unicellular motile, filamentous. | Isogamous |
| Chrysophyceae | Cold freshwater and marine | Brown or orange, Phycochrysin accessory pigment | Fat, leucosin | Unicellular motile, branched filamentous, unequal anterior flagella, two parietal chromatophores | Isogamous |
| Basillariophyceae | All habitats | Yellow or golden brown | Fat, volutin | Unicellular colonial. | Diploid forms, plasmogamy. |
| Cryptophyceae | Marine and freshwater. | Diverse pigments and usually parietal | Carbohydrates and starch. | Motile cells in coccoid with unequal flagella | isogamous |
| Dinophyceae | Marine planktons, a few freshwater forms | Chromatophores are dark yellow and brown. | Starch, oil | Unicellular motile or branched filaments | Isogamous |
| Chloromonadineae | Freshwater | Chromatophores bright green, excess chlorophyll | Oil | Motile with two equal flagella | Chromatophores are dark yellow, and brown. |
| Eugleninae | Freshwater | Longitudinal division | Polysaccharide, Paramylon | Motile, anterior flagella one or two, large nucleus, prominent vascular system. | Isogamous |
| Phaeophyceae | Marine | Chl a, Chl c, carotenes, xanthophylls | Mannitol, laminarin, fats. | Simple filamentous or bulky parenchymatous, giant size with internal differentiation. | Isogamous to oogamous with varied types of life cycles. |
| Rhodophyceae | Fresh water and marine | Chromatophores red-blue r-phycoerythrin and r-phycocyanin, Chla, Chl d, and carotenes | Filamentous, complex structures, no motiles known. | Floridean starch | Oogamous and later carpospores. |
| Myxophyceae(Blue-green algae) | Marine, freshwater, moist places | Chlorophyll, carotenes, xanthophyll, c-phycocyanin and c-phycoerythrin | Sugars, glucogen | Filamentous, with true or false branching, rudimentary nucleus, ps pigments through the cell, non-motile | Fission, No sexual reproduction |
Apart from these 11 classes, Nematophyceae, a fossil group with two genera, was also suggested by Fritsch. True affinities of this class are unknown but their internal morphology is similar to Chlorophyceae. Their spore tetrads are similar to Rhodophyceae.
References
- Botany for Degree Students: Algae by Vashishta B.R./ Sinha A.K. & Singh V.P
- Kumar Singh. (n.d.). Classification of Algae by Fritsch. Marwari College. Retrieved April 12, 2024, from https://marwaricollege.ac.in/study-material/385163146Classificationof%20Algae%20by%20Fritsch.pdf
