Press release

The Sea Lettuce Ulva only gets into shape with the right bacteria

The genus Ulva grows as a tube or a ‘lettuce’ flat, sheet-like blade, as shown for these species collected at the Portuguese coast. The interactions between the juvenile algae and bacteria can be studied under controlled conditions in the laboratory (right). Photos and © Thomas Wichard, University of Jena.

Ulva, a green seaweed found in oceans all over the world, has been selected ‘Alga of the Year 2015’. This ’sea lettuce’ either forms tubular ribbons or sheet-like (‘lettuce’) blades. Individuals commonly reach a size of approx. 20-30 cm. The specific ‘lettuce’ growth form of the alga only develops in association of bacteria which trigger differentiation and development. As Ulva requires the presence of these bacteria, it has developed special mechanisms to attract them. This requires an exchange of information between algae and bacteria. As the two organisms belong to two very different evolutionary groups, this process has fascinated chemists, biologists and algal researchers who now want to establish one Ulva species - namely Ulva mutabilis - as a future model organism.

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Press release

More images / video of the alga Ulva mutabilis

Bacteria-free Ulva mutabilis-cultures develop into an undifferentiated mass of cells (left). Only the association with appropriate bacteria allows Ulva mutabilis to form its natural morphology. The bottom right hand part picture of the panel shows normally developed young algae, which later form a lettuce blade (“sea lettuce”). Photos and © Taghreed Alsufyani, Anne Weiss und Thomas Wichard, University Jena.

Photos of the press release "Alga of the Year 2015: The Sea Lettuce Ulva only gets into shape with the right bacteria


Use of the images is only permitted in connection with reporting on the topic ‘alga of the year 2015’ and only if the photographers are acknowledged in the format: first name, second name, institution. Commercial use of the images is not permitted.

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Literature and Links

European Network Phycomorph

Løvlie A (1964): Genetic control of division rate and morphogenesis in Ulva mutabilis Føyn. CR Trav. Lab. Carlsb. Comptes. 34, 77-168.

Smetacek V and Zingone A (2013): Green and golden seaweed tides on the rise. Nature 504, 84-88.

Spoerner M, Wichard T, Bachhuber T, Stratmann J, and Oertel W (2012): Growth and thallus morphogenesis of Ulva mutabilis (Chlorophyta) depends on a combination of two bacterial species excreting regulatory factors. J. Phycol. 48, 1433-1447 doi:

Contacts for the media

Dr. Thomas Wichard

Head of the research group “Chemical Ecology of Ulva
University of Jena
Institute for anorganic and analytical chemistry
Friedrich-Schiller-Universität Jena

Phone: ++49 3641 948184

E-mail: Thomas.Wichard[at]

Further Information

Members of the Phycology Section (Algology) ( conduct research on algae and investigate, amongst others, taxonomical, ecological, physiological and molecular topics on macro- and microalgae. The Section promotes algal research and supports young scientists. The Section is one of five subject-specific Sections of the German Society for Plant Sciences (Deutsche Botanische Gesellschaft, DBG,

Text: Dr. Esther Schwarz-Weig: and Dr. Thomas Wichard
Translation: Dr. Inka Bartsch (Alfred Wegener Institute) and Dr. Dagmar Stengel (National University of Ireland, Galway)