Photo courtesy of Courtney Miller

What we learned in Class(ification)

Close-up of Fucus vesiculosus - Courtesy of Ester SerraoDomain- Eukaryotic
Kingdom- Chromista
Phylum- Heterokontophyta
Class- Phaeophyceae
Order- Fucales
Family- Fucaceae
Genus- Fucus
Fucus vesiculosus

Domain - Eukaryotic
All organisms within this domain have a true nucleus and membrane bound organelles.

Kingdom - Chromista
Chromista translates into the word "colored." Organisms within this kingdom are mostly photosynthetic. They also contain chlorophyll c, which is what sets this kingdom apart from the kingdom plantae, who do not contain this chlorophyll (plants).

Phylum - Heterokontophyta
Organisms within this phylum have sperm
that possess flagella of unequal lengths, one is on the anterior portion of the sperm, which is useless for motility, and one is a posterior flagellum that the sperm uses for movement. Sperm also have an eyespot located near the anterior end of the cell. The eyespot is used as a photoreceptor organ, and is used to direct the cell.

Class - Phaeophyceae
This is the class that all brown algae reside in. The brown algae derive their color from large amounts of a pigment called fucoxanthin in their chloroplasts.

Order - Fucales
The organisms in this order are parenchymatous with growth from an apical cell, which is at the tip of the blade. The haploid generation (the part of the lifecycle that only has one set of chromosomes) is reduced to an egg and sperm, and the rest of the life cycle is diploid. The sperm and egg are born in a conceptacles, special cavities where only the gametes are borne.

Family - Fucaceae
Algae within this family are the only ones with a four-sided apical cell at maturity. The branching is basically dichotomous and in one plane, although some genera have monopodial branching.

Another Brown Algae in the Fucus genus - Courtesy of Tom VolkFucus vesiculosus - Courtesy of Ester SerraoAnother species of Brown Algae - Courtesy of Tom VolkFucus vesiculosus of the White Sea in Russia - Courtesy of Ester Serrao

Genus - Fucus
Species within this genus have blades that are very branched and supported by a narrow stalk that is attached to a discoid holdfast. The blade has a flattened segment having a central midrib (a prominent vein-like structure)  surrounded on both sides by a narrower wing.

Species - Fucus vesiculosus
The specific classification of F. vesiculosus. Vesiculosus translated from Latin means literally "covered with tiny bladders or blisters." The species is usually found with bladders in pairs on its thallus, and smooth edges around the outside of the blade (the picture above the genus description isn't very typical since the edges look slightly serrated).

"The Tree(s) of Life"
The following images phylogenetic trees that show where F. vesiculosus fits in among other organisms. The tree on the left (Phylogenetic Tree A) shows a larger classification of organisms, from animals, which humans are in (Genus Homo) down to the brown algae where F. vesiculosus fits in. The tree on the right (Phylogenetic Tree B) shows where F. vesiculosus fits in among other brown algae.

Phylogenetic tree - Courtesy of Don Kapraun


 Phylogenetic tree - Courtesy of Ester Serrao and her colleagues

Phylogenetic Tree A

Phylogenetic Tree B

Phylogenetic tree A shows the Fucus genus relative to a broader set of genera than the one found to the right. This classification of genera is based off of a small-subunit (SSU) of Ribosomal Ribonucleic acid (rRNA). This testing is used a lot to classify different organisms and their origins relative to others. The tree was made by Donald F. Kapraun out of the University of North Carolina-Wilmington in 2004.

Phylogenetic tree B shows where F. vesiculosus fits in among other types of brown algae. The basis for this tree was an internal transcribed spacer within the species' nuclear ribosomal DNA. Ester Serrão, Lawrence Alice and Susan Brawley out of the University of Maine used samples of these species to come up with this phylogenetic tree in 1999. This is an older version of the phylogenetic tree, but there is new data under review that further resolves the position of F. vesiculosus relative to its neighbors.

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