“Jelly Bags” Seaweed at Port Eynon

"Jelly Bags" seaweed: Fucus spiralis Linnaeus (also known as "Jelly Bags" seaweed, Spiral Wrack, and Flat Wrack) showing numerous swollen reproductive bodies at the ends of the fronds, on Port Eynon beach, Gower, South Wales, UK (1)  

A couple of things were especially interesting about the Spiral Wrack on Port Eynon beach late in June. The first was the abundance of it and the profusion of the yellow reproductive bodies (scientific name receptacle, common name jelly bags). The second was the variety of sizes, shapes, and different stages of development  of these receptacles – and the presence of a number of unusual structures that can be classified as abnormal.

Spiral Wrack (Latin name Fucus spiralis Linnaeus; alternative common names Flat Wrack and Jelly Bags) is a common British seaweed. It lives in the mid-shore zone below the Pelvetia canaliculata zone (Channelled Wrack) of the upper shore, and above the Fucus vesiculosus (Bladder Wrack) and Acophyllum nodosum (Egg or Knotted Wrack) zones of the lower shore. It is exposed to the air for long periods of time between high and low tides. This alga is hermaphrodite with male and female reproductive structures on the same individual. 

The receptacles of Spiral Wrack are developed as swollen tips, often bifurcate or forked, at the ends of the fronds. Cryptostomata, that elsewhere on the fronds remain as sterile pits containing only hairs, develop in this location as fertile conceptacles that produce both male and female gametes.  Typically receptacles are broadly ellipsoidal to almost spherical and when full, ripe, and full of mucilage, are sometimes called jelly bags

On some fronds there are  also smooth, elongated, swollen structures without the small protruberances and pores that are seen on receptacles. Examples of these can be seen well in Photograph 5. This unusual feature looks like a blister; and specimens of Fucus spiralis with blistered fronds are, apparently, not uncommon. These blisters are not to be confused with air bladders - like the ones found in Fucus vesiculosus. They are instead an irregularity or abnormality, with varying shape and size, thought to be due to some adverse conditions in the environment. They lack the regular, defined, shape of an air vesicle which is inherent in the structure of seaweeds such as Bladder Wrack and Egg Wrack. Perhaps recent encroachment by sand and partial burial in this part of the beach has stressed a seaweed that is normally free to float upwards in seawater while attached to rocks.

“Jelly Bags” seaweed might also be good for the feet. Walking barefoot through the squelching masses could have a certain therapeutic effect (if you don’t slip over first). However, for the most benefit, soaking the feet with a few handfuls of the jelly bags in a bucket of hot water and salt is traditionally thought to be an efficaceous treatment for corns!

Click her for more posts about Spiral Wrack on Jessica’a Nature Blog:

Flat or Spiral Wrack from Chapmans Pool

Three brown seaweeds: Furbelows, Sea Belt, and Spiral Wrack from Studland Bay in spring 

Seaweed on Gower beaches: Fucus spiralis Linnaeus (also known as "Jelly Bags" seaweed, Spiral Wrack, and Flat Wrack) showing numerous swollen reproductive bodies at the ends of the fronds, on Port Eynon beach, Gower, South Wales, UK (2)

Fucus spiralis Linnaeus (also known as "Jelly Bags" seaweed, Spiral Wrack, and Flat Wrack) showing a close-up of the swollen receptacles at the ends of the fronds, on Port Eynon beach, Gower, South Wales, UK (3)

Jelly Bags seaweed drying out between tides: Fucus spiralis Linnaeus (also known as "Jelly Bags" seaweed, Spiral Wrack, and Flat Wrack) showing the swollen receptacles at the ends of the drying fronds, on Port Eynon beach at low tide, Gower, South Wales, UK (4)

Spiral Wrack receptacles and blisters: Fucus spiralis Linnaeus (also known as "Jelly Bags" seaweed, Spiral Wrack, and Flat Wrack) showing the swollen reproductive receptacles in various stages of development, and elongated blisters which are not reproductive in function, on Port Eynon beach, Gower, South Wales, UK (5)

View of Port Eynon looking north-east, showing Fucus spiralis drying out on rocky outcrops and sand exposed at low tide, Gower, South Wales, UK (6)

Spiral wrack at Port Eynon: View of Port Eynon looking north from the shore by the Salt House, showing Fucus spiralis just exposed by the ebbing tide, Gower, South Wales, UK (7) 

Seaweed reflecting the setting sun at Port Eynon: Detail of Fucus spiralis L. (Spiral Wrack, Flat Wrack, or "Jelly Bags") wet and glowing golden in the setting sun, at Port Eynon, Gower, South Wales, UK (8)

Close-up of Fucus spiralis L. (Spiral Wrack, Flat Wrack, or "Jelly Bags") wet and glowing golden in the setting sun, at Port Eynon, Gower, South Wales, UK (9)

COPYRIGHT JESSICA WINDER 2011

All Rights Reserved

Toothed Wrack on Worms Head Causeway

Toothed Wrack seaweed, Fucus serratus Linnaeus, close-up detail showing reproductive conceptacles on the receptacle in transmitted light. Specimen from Worms Head Causeway rocks, Gower, South Wales, UK (1)

Toothed Wrack, Fucus serratus Linnaeus, is a common and familiar British seaweed. It grows on rocks of the lower seashore in the inter-tidal zone. The pictures in this post were taken on the Worms Head Causeway in Gower when the seaweed was exposed at low tide.

This algal plant can reach a length of 2 – 3 feet – that is, up to about a metre. A seaweed is not differentiated into a stem, roots and leaves like the higher plants. However, it does have different parts. The plant body, or thallus, has a branched hapteron or holdfast - a root-like structure at its base – by which it is attached securely to the rocks.  The thin ‘branches’ of the hapteron grow into the cracks and crevices to hold the seaweed into position and make it very difficult for the actions of the sea to dislodge it.

A short cylindrical stalk or stipe connects the hapteron to a flat broad branched blade known as the lamina. In Toothed Wrack the edges of the laminae have an irregular serrated (saw-like or tooth-like) edge from which the seaweed gets its name. 

Reproduction in Toothed Wrack is mainly sexual rather than vegetative. At certain times of the year, the terminal few centimetres of the branched laminae become swollen; and these parts are then called the receptacles. Small cavities named conceptacles sit just below the outer layer of the receptacles and are connected to the surface by minute openings known as ostioles. [Actually, these tiny cavities are found in other places on the seaweed but in these locations they are sterile and only contain hairs. If you look closely at  Picture 4 in this post, you should be able to see regular grouping of these small hairs on some of the laminae.]

However, in the receptacles, the conceptacles are fertile and produce the gametes used in sexual reproduction. Fucus serratus L.  has separate male plants and female plants, each producing gametes that are shed through the ostiole into the sea water where fertilisation and development take place. 

Natural pattern and texture in seaweed: Tooth Wrack, Fucus serratus Linnaeus, detail of the swollen rounded conceptacles containing ripening reproductive products on the terminal receptacles - macro photograph in reflected light showing surface texture. Specimen from Worms Head Causeway, Gower, South Wales, UK (2)

Toothed Wrack, Fucus serratus Linnaeus, showing the branched receptacles bearing the conceptacles at the end of the lamina, blade or frond of the alga. Specimen photographed on Worms Head Causeway, Gower, South Wales. UK (3) 

Toothed Wrack, Fucus serratus Linnaeus, showing branched reproductive receptacles at the end of a flat, tooth-edged lamina. Growing specimen exposed at low tide on Worms Head Causeway, Gower, South Wales, UK (4)

Seaweed of the Gower Peninsula: Toothed Wrack, Fucus serratus Linnaeus, showing branched reproductive receptacles at the end of a flat, tooth-edged lamina. Growing specimen exposed at low tide on Worms Head Causeway, Gower, South Wales, UK (5)

Toothed Wrack and Coral Weed growing together: Olive-green Toothed Wrack, Fucus serratus Linnaeus, growing among purple Coral Weed, Corallina officinalis Linnaeus, exposed at low tide on the lower shore at Worms Head Causeway, Gower, South Wales, UK (6)

Common British seaweeds of the lower rocky shore: Toothed or Serrated Wrack, Fucus serratus Linnaeus, on the lower rocky shore with other common British seaweeds, exposed by a very low tide at Worms Head Causeway, Gower, South Wales, UK (7)

COPYRIGHT JESSICA WINDER 2011

All Rights Reserved