[352] Ulva intestinalis, Gutweed and Green Algae

[352] Ulva intestinalis, Gutweed

Ulva lactuca, Sea Lettuce

Introduction

Ulva intestinalis, Gutweed, and Ulva lactuca, Sea Lettuce, are two types of common seaweed representing all the species of Green Algae.

All species of Ulva are sometimes called Sea Lettuce. Ulva intestinalis has been reclassified fairly recently. It used to be Enteromorpha intestinalis. [None of the other Ulva species have any specific common names.]

Sonchus arvensis, a close relative of [081] Chicory, has many common names that include Gutweed.

Taxonomy

Domain – Eukaryotes

Clade – Green Plants (Green Algae and Land Plants)

Phylum (or Division) – Chlorophyta

Class – Ulvophyceae

Order – Ulvales

Family – Ulvaceae (Flat or tubular green algae)

Genus – Ulva (Sea Lettuce)

Scientific Names – Ulva intestinalis, Ulva lactuca

Ulva intestinalis has the scientific synonym Enteromorpha intestinalis.

Groups above the Class level are debatable. They don’t usually have a level corresponding to Kingdom.

Name

The Classical Latin ulva is assumed to mean sedge (See [068] Hanging Sedge,) which is associated with water but is a long way from any green algae. Lactuca is the Modern Latin genus name for lettuce. Gutweed, intestinalis and Enteromorpha are all derived from the tubular nature of this plant.

Green Algae

What most people call seaweed consists of many species of Green Algae, Red Algae, Brown Algae and other types of Algae. I will not examine these in detail but, as you might expect by now, the actual colour of anything you see is only a very loose clue as to its classification.

We have already looked at [079] Red Algae and [151] Brown Algae and all I will add here is that Green Algae normally just creep to the widest definition of plants, where Red Algae or Brown Algae are normally just outside. Their green colour comes from the chlorophyll that defines plants.

The clade Chlorophytes (sometimes treated as a phylum or division) is one several groups that make up Green Algae.

The structures of Green Algae species are very simple. Many species, but not those in the order Ulvales, are single-celled.

As noted in [141] Oakmoss, many species of Lichen have Green Algae as their phycobiont.

Ulva lactuca

Sea Lettuce looks like a bright green, floppy flat leafy structure, somewhat like a lettuce leaf.

There are over a hundred species of Ulva, some of which may occur in Britain and some of these may look very similar to Ulva lactuca.

It has a worldwide distribution and is best found on sandy beaches or rocks between the high tide and low tide lines.

It is edible and has been used as a food source.

Ulva intestinalis

This species consists of long, very thin tubes of bright green, generally seen attached to rocks in tidal areas.

It is found almost worldwide.

Other Notes

Although I wanted to cover all Green Algae in this blog, there are no other common species – apart from some close relatives within the genus Ulva that may be confused with these two.

[151] Fucus vesiculosus, Bladder-wrack

[151] Fucus vesiculosus, Bladder Wrack – and other Brown Algae

Introduction

Fucus vesiculosus, Bladder Wrack or (Bladder-wrack), is a very common seaweed. To be more precise it is a species of Brown Algae and I will consider other Brown Algae in this blog.

Taxonomy

Kingdom – Chromists

Superphylum – Heterokonts/ Straminopiles (or Stramenopiles)

Phylum – Ochrophyta (Mostly photosynthetic heterokonts with red-algal plastids)

Class – Phaeophyceae (Brown Algae)

Subclass – Fucophycidae

Order – Fucales

Family – Fucaceae

Genus – Fucus

Scientific Name – Fucus vesiculosus

See text for other species.

Name

Wrack is cognate with wreck and used to mean anything washed ashore from a seawreck, and hence, anything washed ashore such as seaweed.

The Latin fucus meaning lichen or a red dye comes from Ancient Greek phukos meaning seaweed. Vesicula is a diminutive from the Latin vesica meaning bladder.

Brown Algae

I have to say something about Brown Algae. The ones we see are common types of seaweed and most people would normally think of them as plants – but the taxonomy is complex, as you may remember from [079] Carrageen, which considered Red Algae.

Of the three types of Algae that we normally consider as seaweed, Red Algae and [352] Green Algae just creep into the edges of what are normally considered to be plants but Brown Algae comes outside. Don’t ask me why.

Brown Algae form a Class, Phaeophyceae. I will not attempt to explain Heterokonts or any of the taxonomic levels above and below Phaeophyceae but will just say a little about a few species, with some pictures.

[As you may have guessed, one reason for not trying to explain is that I really don’t understand myself.]

All of my Brown Algae pictures come from the intertidal areas of the Isle of Wight coast. The first four species listed below are the most common forms of seaweed found on the British coasts.

(1) Fucus vesiculosus, Bladder Wrack

Fucus vesiculosus has other names including Dyer’s Fucus and Red Fucus. It was the original source of Iodine, discovered in 1811 and has been used to treat diseases related to iodine deficiency.

It is between dark brown and olive brown and has long, flat fronds, with almost spherical air bubbles that give it its name.

Bladder Wrack is the most common seaweed found all around the shores of the UK. It can also be found on the coasts of the North Sea, the Baltic Sea and the northern coasts of the Atlantic Ocean.

It is only found between high tide and low tide levels. I found a large quantity of it on the rocky shore just below Osborne House on the Isle of Wight.

(2) Fucus spiralis, Spiral Wrack, comes from the same Genus.

It has the same area of natural distribution and its fronds are similar in colour but it doesn’t have the air bladders of Fucus vesiculosus.

(3) Fucus serratus, Serrated Wrack (or Toothed Wrack), also from the same Genus.

This species is similar to Fucus spiralis but its fronds have serrated edges.

(4) Ascophyllum nodosum, Egg Wrack, from the same family, Fucaceae.

This genus only has one species. It is very similar to Bladder Wrack but the air bladders are more egg-shaped than spherical.

(5) Halidrys siliquosa, from the same Order, Fucales,Family Sargassaceae. (No common name.)

This another very common seaweed with long fronds, somewhat thinner than the first three. It has some air bladders and is native to just the coasts of the British Isles.

(6) Dictyopteris Polypoioides, from another Subclass, Dictyophycidae,Order Dictyotales, Family Dictyotaceae.

This seaweed is flatter and thinner and is found on the southwestern coasts of the UK and elsewhere.

There are many other species of brown algae that are difficult to identify without expert knowledge and microscopic examination. I have decided not to show any pictures because of uncertainty about identification.

See Also

As noted above, Green Algae will come a lot later.

[079] Chondrus crispus, Carrageen

[079] Chondrus crispus, Irish Moss and Red Algae

Introduction

Chondrus crispus, Irish Moss or Carrageen Moss, is a Red Alga found at inter-tidal levels round the coasts of Ireland and other European locations. Despite its name it has nothing to do with moss. I will consider all Red Algae in this blog. [Technically algae is the plural of alga but I may use it as a singular, either countable or uncountable.]

Taxonomy

Kingdom – Plants

Division – Rhodophyta (Red Algae)

Class – Floridophyceae

Order – Gigartinales

Family – Gigartinaceae

Genus – Chondrus

Scientific Name – Chondrus crispus

See the note below about Seaweed.

Name

The word moss has a much wider meaning informally than its botanical definition. There are many examples of algae, lichen etc. being called moss. Carrageen comes from the Irish name of this organism, carraigin, meaning little rock. Chondrus comes from the Ancient Greek khondrus, ‘cartilage.’ from the gelatinous substance it produces when boiled. The Latin crispus means ‘curly.’

Seaweed

Seaweed is a vague sort of term and it can include some species of flowering plants that just happen to live in the sea. But generally, everything we think of as seaweed is either Brown Algae, Red Algae or Green Algae. Whether they are actually plants is a matter of opinion and scientists have different views depending on how they define Plants.

They may talk of Land Plants, which excludes them all, or they may include Green Algae; or Green and Red Algae; or all three. It doesn’t really matter.

We will meet [151] Brown Algae and [352] Green Algae later but my randomizing order of posts brings us first to Red Algae. This post will briefly consider them all.

Red Algae

There are about 7 000 species of Red Algae. 95% of known species of Red Algae are include in the class Florideophyceae, sometimes demoted to a subclass, Florideae.

I won’t say anything about the anatomy or physiology of algae and I will avoid the technical words like stipe, holdfast, lamina and frond. You are unlikely to find any of these organisms other than below the high-tide level on the coast. There natural environment is underwater so anything found on a beach may be dead or dried out. You may need microscopic examination to determine the species.

Irish Moss

As for most red algae, the colour of Chondrus crispus is variable. It can be any colour from yellow-green through red to purple-brown. Superficially it looks much the same as all other algae that you may find at the edge of the sea.

When boiled in water it forms a jelly. This consists mostly of carrageenans, a group of chemicals widely used in the food industry as gelling, thickening and stabilizing agents, and as vegan alternatives to gelatin. They have been used since about 600 BC in China, and since 400 AD in Ireland. Now production, mostly in the Philippines generally uses other species of red algae.

Habitat and use

Chondrus crispus is common on the coasts of Ireland and other Atlantic coasts. It normally attaches to rocks from the middle of the zone between high and low tides down to the sea floor.

It is used to produce carrageenan, known in the EU as E407 or E407a and used for example in making ice-cream or fining beer or wine.

In Asia, South America and the Caribbean it used to make jelly-like desserts. In Ireland and parts of Scotland it is boiled in milk and flavoured with vanilla, cinnamon, brandy or whisky to make something like blancmange or pannacotta.

Other Notes

All my pictures of Algae come from a visit to the Isle of Wight recently and were found on the beach – either at the high tide level or lower.

They were identified with an identification app and using information from the Internet, and most of my initial identifications were wrong. I have been helped by groups on Social Media sites and I am confident of the title picture as Chondrus crispus. For my remaining pictures I will give a possible identification where I have one but I won’t say any more about other species.

These are Furcellaria lumbricalis, used commercially for carrageenan; Gracilaria sp, used as food, to produce gelatin and in aquariums; Halopiythys incurva; and Osmundea sp.

The following are unidentified. Some of them may possibly be brown algae!

See also

Two more generic posts will consider [151] Brown Algae and [352] Green Algae.