I’ve talked about Flat or Spiral Wrack (Fucus spiralis Linnaeus) before but wasn’t able to show a good photograph of one of its defining features. Getting close-ups of details on the seashore is sometimes impossible – without lying full-length face-down in wet seaweed. So the last time I was on the beach I collected a few fronds of Flat Wrack, from the extensive beds of Fucoids that covered the flat rock platform on the eastern shore of Chapmans Pool, and took them home to get the photographs that I wanted in comfort.
The pictures above and below illustrate the way that the swollen granular reproductive bodies at the ends of the fronds in this species have a unique flat border – like a seam – around the edge. You can see this border both flat-on and edge-on in the photographs. In other characteristics Flat or Spiral Wrack could be mistaken for another species of Fucoid brown seaweed but it is the only one with this particular characteristic.
The rock platform on the eastern edge of Chapmans Pool in June was covered in an olive green carpet of short Fucoid seaweeds including, Toothed Wrack, Bladder Wrack, and Flat or Spiral Wrack.
You have to look closely to see that the seaweed bed is composed of all the different types of weed, growing together, and overlapping each other in a complex natural mosaic pattern.
In the picture below you can see the round pea-shaped air bladders that occur in Bladder Wrack. There are fronds like this on the left side of the picture. The golden yellow-green reproductive bodies on the forked tips of the Flat Wrack are quite distinct elsewhere in the photograph. Both seaweeds have a central midrib along the fronds.
Previously, Flat or Spiral Wrack was discussed in the earlier post Three brown seaweeds: Furbelows, Sea Belt & Spiral Wrack from Studland Bay in spring.
Revision of a post first published 5 June 2010
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Jessica's Nature Blog 
Dear Jessica:
Your blog is very interesting and informative. I enjoy it very much. Recently, I was on a beach of Somerset (TA24 5SH). I found a grape-shaped gel-filled sea plant on the beach. It is similar to falt wrack but filled with gel. It is black and like a branch of pea-size grapes. It has many thin films enclosing the inside gel. Do you know the name of it? I am sorry I didn’t take a picture of it.
cheers
Jindong
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Dear Jindong. It is a bit difficult to identify something without a photograph, so I might be wrong, but from your description I think you may have been looking at a bunch of cuttlefish eggs rather than the fruiting bodies of a seaweed. There is some information about this in another posting on Jessica’s Nature Blog called “Cuttlefish Eggs at Rhossili” at https://natureinfocus.wordpress.com/2009/10/08/cuttlefish-eggs-at-rhossili/. The eggs shown in the pictures are not perfectly spherical but the overall impression is like a bunch of black grapes. Does this look like what you found in Somerset?
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you are super star! That’s exactly what I saw. I am very interesting at the delicate structure of the egg. I guess the film can protect the egg from being dehydrated under the sun. Each time I bring my children to the beach, I feel sorry to my thin knowledge to the sea creatures. Your blog is a very good collection about these information. Do you read a lot books about rocks, animals and plants? Any suggestions to us?
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There are Many good books about seashore life – but one I like a lot, especially for beginners and children, is Judith Oakley’s “Seashore Safaris” https://natureinfocus.wordpress.com/2014/01/11/seashore-safaris-by-judith-oakley/.
I will have to give some thought as to which books to recommend for rocks and plants. I usually use more academic works for identifications of these. I will get back to you with some suggestions later.
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Thanks Jessica! I have bought it and cannot wait to read it.
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I hope you enjoy using it and find the information you need about seashore life. Have fun.
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