Whilst bladder wrack is the best known of the wrack seaweeds the one most often seen is actually the channelled wrack (Pelvetia canaliculata). Growing freely near the high water line it is adapted to withstand long periods of exposure to the air without drying out. The weed that is out of the water the longest is usually blacker than the paler colour of that which is covered for longer. It does not have bladders for flotation as it rarely needs to float. It may appear to have bladders at the ends of its fronds but the swellings are not full of air, they contain a jelly substance and are the fruiting body of the seaweed.
Channelled wrack grows in large masses and can be seen on sea walls, quays and piers as well as the upper reaches of rocky shorelines but each plant only grows to about 18 inches long due to the amount of time it is our of water. It is common around British shores and Dorset is no exception to that. In Scotland it has been used as cattle fodder but I was surprised to read on the 'justaseaweed' website that this is considered to be a super healthy food and by far our most popular sea vegetable. It apparently looks fantastic on a plate and is very quick to prepare needing only a few seconds of boiling. The culinary possibilities of this seaweed are limitless. I am sure they are right but as they are selling it I might try it with a pinch of salt!