According to recent phylogenetic studies of evolutionary relationships, some algae the red algae and most green algae are indeed most closely related to the land plants, but other algae are related to certain protist groups.
Thus, the algae are a highly variable and genetically diverse group of organisms belonging to many different evolutionary lineages. This diversity is reflected in the enormous variation exhibited by algae in terms of morphological, ultrastructural, ecological, biochemical, and physiological traits.
Algae of one kind or another have been around for more than 2 billion years. New algae are being discovered all the time, even entirely unknown phyla or classes. Seaweeds : Multicellular marine algae, or seaweeds, are plant-like organisms that generally live attached to rocks or other hard substrata in coastal areas.
They belong to three different groups, recognized since the mid-nineteenth century on the basis of thallus color: red algae phylum Rhodophyta , brown algae phylum Ochrophyta : class Phaeophyceae , and green algae phylum Chlorophyta. As a result of modern investigations ultrastructural and biochemical studies and, more recently, phylogenetic analyses based on DNA sequencing , we now know that the differences among these three groups run far deeper than the color differences suggested by their names.
Some of the larger brown algae known as kelps, such as the giant kelp Macrocystis pyrifera , exhibit translocation internal transport of organic materials and nutrients and a similar process has been shown to occur in the green Charophytes, but translocation is not seen in most algal groups.
In general, however, algae have little need for transporting nutrients through their bodies because they are, at some stage, surrounded by water and individual cells can therefore exchange materials directly with their surroundings. Phytoplankton : Phytoplankton are the drifting, photosynthetic, mostly microscopic algae and cyanobacteria that capture energy from the sun and form the foundation of food webs in freshwater and marine habitats.
Tang and his colleagues discovered the fossils near Dalian City in Liaoning province of northern China. They had heard there was "a thick pile of well-exposed sedimentary rocks" from the Nanfen Formation dating to about a billion years ago.
So, Tang took some of these ancient rocks, mostly mudstone and shale, back to the lab at Virginia Tech. Tang was "really excited" when he saw the algae fossil under the microscope.
In all, he identified 1, specimens. Just like modern-day algae, P. It likely played an important role in the ancient ecosystem by producing oxygen , he said. In addition, it likely provided food and shelter to other organisms. Life on Earth is dependent on photosynthesizing plants and algae for food, yet land plants did not evolve until about million years ago, Tang said.
These fossils came from an ancient ocean, but there is still a debate about where green algae originated. Moreover, green algae isn't the oldest algae on record. The development of autotrophic green algae from cells that engulfed photosynthetic bacteria 3. Another important turning point in the history of eukaryotic life—also mediated by algae—is the colonization of land by around million years ago.
With this event, the atmospheric oxygen concentrations skyrocketed as a result of photosynthetic activity aboveground, and a path to terrestrial life was established Wodniok Over millions of years, algae developed into the first nonvascular land plants, which evolved into the complex seed plants like gymnosperms and angiosperms we see in botanic gardens today de Vries, Even if these early algae and land plants are not as prevalent as they were millennia ago, their existence created the diverse flora that are so admired by many environmentalists.
One flaw in most ecological arguments is the overlooking of the small details of the past. We only look toward the future—which organisms can replace bees as pollinators? Out of all these endangered species, which animals should we prioritize saving? How much should each person have to contribute to scale back carbon emissions by a certain year? If one single cellular organism could give rise to every plant we see outside our window, should we not consider the effect our smallest actions?
We are an incredible species, but our powerful sphere of influence could lead to the closing chapter of the history of life on Earth. The actions we do are irreversibly written into history—who will we be remembered as by our descendants?
Or will there be no one left to remember us by? Though algae have given us the gift of life as we know it today, it may also be our downfall. Given the previously outlined importance of algae to life as we know it today, one might question why this abundance of algae could be detrimental. Runoff of phosphorus-rich fertilizers into lakes and streams from agricultural engineering projects have caused a problem known as eutrophication.
These algal blooms accumulate in surface water, where they produce toxins that kill fish and other aquatic life. Schindler Hypoxic areas are caused by algae that monopolize all the oxygen in an aquatic ecosystem. As seen in the map above from , the number of eutrophic and hypoxic coastal are becoming much more prevalent around the world. With the development of large scale commercial farming needed to sustain the growing global population, agricultural runoff has not only increased the frequency of algal blooms in the Beibu Gulf of China from six events between and to approximately twenty between to , but has also increased the surface area of such blooms from tens to hundreds of square kilometers Xu As seen in the persisting problem of eutrophication, it is evident that although a single alga may not be able to significantly impact our day-to-day life, a teeming colony could have detrimental effects on society as well as ecology.
Like algae, we are a community species, where parts add up to a whole.
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