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Society for the History of Natural History

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Ancient seaweed is living fossil

Ancient seaweed is living fossil

By Matt Walker, Editor, Earth News

Ancient seaweed that have been found growing in the deep sea are "living fossils", researchers have reported. The two types of seaweed, which grow more than 200m underwater, represent previously unrecognised ancient forms of algae, say the scientists. As such, the algae could belong to the earliest of all known green plants, diverging up to one billion years ago from the ancestor of all such plants. Details of the discovery are published in the Journal of Phycology.

"The algae occur in relatively deep marine waters – 210m, which is certainly deep for a photosynthetic organism," Professor Frederick Zechman told the BBC. "They can be found in shallower water but typically under ledges in low light. "They appear to possess special chlorophyll pigments that allow them to utilise the low intensity blue light found at depth."

Professor Zechman of California State University in Fresno, US, sampled the seaweeds with a team of researchers based across the US and in Belgium. The algae had previously been identified. They belong to the scientific groups, or genera, called Palmophyllum and Verdigellas. But Professor Zechman’s team is the first to study their genetic make-up, and it is this research that has revealed their startling ancestry.

Green origins

Green plants in general belong to one of two groups, or clades. One clade includes all land plants and the green algae with the most complex structures, known as charophytes or more commonly stoneworts. The other clade, known as the Cholorophyta, comprises all other green algae. Most studies have sought to determine what ancient plants gave rise to the land plants and stoneworts. But little research has been done into the origin of the other green algae. So Professor Zechman’s team collected and studied Palmophyllum algae from New Zealand waters and Verdigellas from the western Atlantic Ocean.

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