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Porphyra umbilicalis (tough laver)

On the shore you will see the blade phase of Porphyra umbilicalis.

Identifying features

  • the blade is light to dark reddish-brown
  • the blade can be very variable in shape and form
  • it is only one cell layer thick and translucent
  • it develops from a very small disc called the holdfast
  • a common form is where the blade expands around the holdfast and appears pleated or resembles a rosette or a little cabbage
  • individuals are usually about 5–10 cm tall

Porphyra species have complex life histories. The blade that you see on the shore is just a part of the life history. There is a separate, microscopic phase that lives in shells and is called the conchocelis phase. Look for pink patches on shells because these might be evidence of conchocelis.


Porphyra umbilicalis is a common species and does not appear to be threatened. However, because part of its life history is hidden in the shells of animals, we should not be complacent. We know very little about the tolerance of the conchocelis phase and do not know how it will respond to influences such as climate change and ocean acidification.

Species detail

There are several other species of Porphyra that can grow with P. umbilicalis. These species are almost impossible to tell apart by shape alone. However, molecular studies are helping scientists identify species, and discover relationships between species.

  • Porphyra umbilicalis

    Porphyra umbilicalis occurs on shores in the North Atlantic. Find out exactly where, and on what, it lives.

  • Porphyra umbilicalis specimen

    Find out more about the complex life-history of this seaweed.

  • Porphyra umbilicalis

    Get more information on Porphyra umbilicalis.


Porphyra umbilicalis specimen

Porphyra umbilicalis specimen.

Porphyra umbilicalis

Porphyra umbilicalis in Iceland.

Porphyra umbilicalis

Porphyra umbilicalis in Iceland.

Photo of Juliet Brodie
Prof Juliet Brodie

Research Chair, Division of Genomic and Microbial Diversity, Department of Life Sciences.

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Phase of the seaweed’s life history when it has filaments and lives inside an animal shell. This phase is only seen in the Bangiophycidae - the class of red algae to which Porphyra umbilicalis belongs.


The phase of a plant's life history when all the cells are haploid - they contain only a single set of chromosomes (half the number found in the adult). The haploid gametophyte is typically formed by division of a diploid (full chromosome set) sporophyte.