10 Marine Macro- and Microalgae: An Overview
The Ochrophyta possess chlorophyll a and c (with the exception of the Eustigmatophyceae that
only have chlorophyll a), β carotene, and various xanthophylls responsible for the typical greenishbrown coloration. The main food reserve is the complex carbohydrate polymer laminarin. Mannitol, a
low molecular sugar-alcohol, can also be present and is thought to serve also as a reserve food and as an
osmoticant (Bold and Wynne 1985). The cell structure is eukaryotic, with a distinct cell wall containing
alginate compounds and cellulose. Typically, cells are uninucleated with the exception of the medullary
cells in Durvillea and Laminaria.
The sexual life cycle can be haplontic (Chysophyceae), diplontic (Bacillariophyceae), and
diplohaplontic (Paeophyceae) and can be iso- or hetermorphic (Bold and Wynne 1985).
As in the Rhodophyta, there are many brown algae species important economically, used as direct
food source, commercial colloids extracts, and additives for several purposes (Graham et al. 2009).
Haptophyta
The 300 known Haptophyta (Graham et al. 2009) encompass simple organisms including unicellular,
palmelloid, or coccoid forms, and also a few colonies and short filaments. The flagellate cells bear
two naked flagella with different lengths, inserted apical or laterally. The algae of this phylum possess
a haptonema, a long thin organelle somehow similar to a flagellum but with a distinct ultrastructure
(Barsanti and Gualtieri 2014).
Haptophytes are predominantly marine, with only a few records from freshwater and terrestrial
systems. The best-known are coccolithophores, some of the most abundant marine phytoplankton,
especially in the open ocean. These organisms have an exoskeleton of calcareous plates called coccolith and
are extremely abundant as microfossils. Other well-known planktonic haptophytes are Chrysochromulina
and Prymnesium, which periodically form toxic marine algal blooms (Graham et al. 2009).
The Haptophyta possess chlorophyll a and c, β carotene, and various xanthophylls responsible for the
typical golden yellow-brown coloration. The main food reserve is the polysaccharide chrysolaminarine.
The cell wall is covered with tiny cellulosic or calcified scales bearing spot-like fibrils which are radially
arranged.
Their sexual life cycle is hetermorphic diplohaplontic, in which a diploid planktonic flagellate stage
alternates with a haploid benthic filamentous stage.
Cryptophyta
This cryptophytes are simple unicellular flagellate asymmetric organisms that bear two unequal hair
flagella, subapically inserted parallel to one another, covered by bipartite hairs, and emerging form a
deep gullet located on the ventral side of the cell. The 200 known species are typically free-swimming
organisms in both marine and freshwater systems. Some members are known to be zooxanthellae in host
invertebrates or within marine ciliates.
Cryptophyta possess chlorophyll a and c, α carotene, and various phycobilins. The main food reserve
is starch granules. The cell is enclosed in a stiff, proteinaceous periplast made of polygonal plates.
Cryptomonads are distinguished by the presence of characteristic extrusomes called ejectosomes, which
consist of two connected spiral ribbons held under tension (Graham et al. 2009).
Although a sexual life cycle has been recently reported, the main method of reproduction is by
longitudinal cell divisions (Barsanti and Gualtieri 2014).
Miozoa (Dinophyceae)
This phylum includes about 3,000 to 4,000 species, the most common being unicellular flagellates.
Ameboid, coccoid, palmelloid, filamentous, and non-flagellate unicellular forms, although less common,
can also occur (Graham et al. 2009). The dinoflagellates have two flagella with an independent beating
pattern and a distinct location, one girdling and conferring the cell the rotator swimming motion, the other
trailing. The cell is surrounded by a layer of flat, polygonal vesicles, which can be empty or filled with
The Ochrophyta possess chlorophyll a and c (with the exception of the Eustigmatophyceae that
only have chlorophyll a), β carotene, and various xanthophylls responsible for the typical greenishbrown coloration. The main food reserve is the complex carbohydrate polymer laminarin. Mannitol, a
low molecular sugar-alcohol, can also be present and is thought to serve also as a reserve food and as an
osmoticant (Bold and Wynne 1985). The cell structure is eukaryotic, with a distinct cell wall containing
alginate compounds and cellulose. Typically, cells are uninucleated with the exception of the medullary
cells in Durvillea and Laminaria.
The sexual life cycle can be haplontic (Chysophyceae), diplontic (Bacillariophyceae), and
diplohaplontic (Paeophyceae) and can be iso- or hetermorphic (Bold and Wynne 1985).
As in the Rhodophyta, there are many brown algae species important economically, used as direct
food source, commercial colloids extracts, and additives for several purposes (Graham et al. 2009).
Haptophyta
The 300 known Haptophyta (Graham et al. 2009) encompass simple organisms including unicellular,
palmelloid, or coccoid forms, and also a few colonies and short filaments. The flagellate cells bear
two naked flagella with different lengths, inserted apical or laterally. The algae of this phylum possess
a haptonema, a long thin organelle somehow similar to a flagellum but with a distinct ultrastructure
(Barsanti and Gualtieri 2014).
Haptophytes are predominantly marine, with only a few records from freshwater and terrestrial
systems. The best-known are coccolithophores, some of the most abundant marine phytoplankton,
especially in the open ocean. These organisms have an exoskeleton of calcareous plates called coccolith and
are extremely abundant as microfossils. Other well-known planktonic haptophytes are Chrysochromulina
and Prymnesium, which periodically form toxic marine algal blooms (Graham et al. 2009).
The Haptophyta possess chlorophyll a and c, β carotene, and various xanthophylls responsible for the
typical golden yellow-brown coloration. The main food reserve is the polysaccharide chrysolaminarine.
The cell wall is covered with tiny cellulosic or calcified scales bearing spot-like fibrils which are radially
arranged.
Their sexual life cycle is hetermorphic diplohaplontic, in which a diploid planktonic flagellate stage
alternates with a haploid benthic filamentous stage.
Cryptophyta
This cryptophytes are simple unicellular flagellate asymmetric organisms that bear two unequal hair
flagella, subapically inserted parallel to one another, covered by bipartite hairs, and emerging form a
deep gullet located on the ventral side of the cell. The 200 known species are typically free-swimming
organisms in both marine and freshwater systems. Some members are known to be zooxanthellae in host
invertebrates or within marine ciliates.
Cryptophyta possess chlorophyll a and c, α carotene, and various phycobilins. The main food reserve
is starch granules. The cell is enclosed in a stiff, proteinaceous periplast made of polygonal plates.
Cryptomonads are distinguished by the presence of characteristic extrusomes called ejectosomes, which
consist of two connected spiral ribbons held under tension (Graham et al. 2009).
Although a sexual life cycle has been recently reported, the main method of reproduction is by
longitudinal cell divisions (Barsanti and Gualtieri 2014).
Miozoa (Dinophyceae)
This phylum includes about 3,000 to 4,000 species, the most common being unicellular flagellates.
Ameboid, coccoid, palmelloid, filamentous, and non-flagellate unicellular forms, although less common,
can also occur (Graham et al. 2009). The dinoflagellates have two flagella with an independent beating
pattern and a distinct location, one girdling and conferring the cell the rotator swimming motion, the other
trailing. The cell is surrounded by a layer of flat, polygonal vesicles, which can be empty or filled with