Ulva lactuca
Encyclopedia
Ulva lactuca Linnaeus, a green alga in the division Chlorophyta
, is the type species
of the genus Ulva
, also known by the common name sea lettuce
.
. The margin is somewhat ruffled and often torn. It may reach 18 cm or more in length, though generally much less, and up to 30 cm across. The membrane is two cells thick, soft and translucent, and grows attached, without a stipe
, to rock by a small disc-shaped holdfast
. Green to dark green in color, this species in the Chlorophyta is formed of two layers of cell
s irregularly arranged, as seen in cross section. The chloroplast
is cup-shaped with 1 to 3 pyrenoid
s. There are other species of Ulva which are similar and not always easy to differentiate.
, North America (west and east coasts), Central America
, Caribbean
Islands, South America, Africa
, Indian Ocean Islands, South-west Asia, China
, Pacific Islands, Australia
http://www.algaebase.org/search/species/detail/?species_id=39&sk=0&from=results and New Zealand.http://www.algaebase.org/search/species/detail/?species_id=39&sk=0&from=results
and sublittoral on shores all around the British Isles
, the coast of France
, the Low Countries
and up to Denmark
. It is particularly prolific in areas where nutrients are abundant. This has been the case off the coast of Brittany
where a high level of nitrates, from the intensive farming there, washes out to sea. The result is that large quantities of Ulva lactuca are washed up on beaches, where their decay produces methane, hydrogen sulphide, and other gases.
Certain environmental conditions can lead to the algae spreading over large areas. In August 2009, unprecedented levels of the algae washed up on the beaches of Brittany
, France
, causing a major public health scare as it decomposed. The rotting thalli produced large quantities of hydrogen sulphide, a toxic gas. In one incident near Saint-Michel-en-Grève
, a horse rider lost consciousness and his horse died after breathing the seaweed fumes. Environmentalists blamed the phenomenon on excessive use fertilizers and the excretion of nitrates by pig and poultry farmers. In a separate incident at the same beach, a truck driver and several schoolchildren died after taking part in the cleanup without protection.
, these settle and grow to form haploid male and female plants similar to the diploid plants. When these haploid plants release gametes they unite to produce the zygote
which germinates, and grows to produce the diploid plant.
U. lactuca is locally used in Scotland
in soups and salads.
Chlorophyta
Chlorophyta is a division of green algae, informally called chlorophytes. The name is used in two very different senses so that care is needed to determine the use by a particular author...
, is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Ulva
Sea lettuce
The sea lettuces comprise the genus Ulva, a group of edible green algae that is widely distributed along the coasts of the world's oceans. The type species within the genus Ulva is Ulva lactuca Linnaeus, "lactuca" meaning lettuce...
, also known by the common name sea lettuce
Sea lettuce
The sea lettuces comprise the genus Ulva, a group of edible green algae that is widely distributed along the coasts of the world's oceans. The type species within the genus Ulva is Ulva lactuca Linnaeus, "lactuca" meaning lettuce...
.
Description
Ulva lactuca is a thin flat green alga growing from a discoid holdfastHoldfast
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. ...
. The margin is somewhat ruffled and often torn. It may reach 18 cm or more in length, though generally much less, and up to 30 cm across. The membrane is two cells thick, soft and translucent, and grows attached, without a stipe
Stipe (botany)
In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
, to rock by a small disc-shaped holdfast
Holdfast
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. ...
. Green to dark green in color, this species in the Chlorophyta is formed of two layers of cell
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
s irregularly arranged, as seen in cross section. The chloroplast
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
is cup-shaped with 1 to 3 pyrenoid
Pyrenoid
In cell biology, pyrenoids are organelles, centers of carbon dioxide fixation within the chloroplasts of algae and hornworts. Pyrenoids are not membrane-bound, but specialized areas of the plastid that contain high levels of ribulose-1,5-bisphosphate carboxylase/oxygenase .RubisCO fixes carbon...
s. There are other species of Ulva which are similar and not always easy to differentiate.
Distribution
The distribution is worldwide: EuropeEurope
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, North America (west and east coasts), Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
Islands, South America, Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Indian Ocean Islands, South-west Asia, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Pacific Islands, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
http://www.algaebase.org/search/species/detail/?species_id=39&sk=0&from=results and New Zealand.http://www.algaebase.org/search/species/detail/?species_id=39&sk=0&from=results
Ecology
Ulva lactuca is very common on rocks and on other algae in the littoralLittoral
The littoral zone is that part of a sea, lake or river that is close to the shore. In coastal environments the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes this intertidal zone and is often used to...
and sublittoral on shores all around the British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
, the coast of France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, the Low Countries
Low Countries
The Low Countries are the historical lands around the low-lying delta of the Rhine, Scheldt, and Meuse rivers, including the modern countries of Belgium, the Netherlands, Luxembourg and parts of northern France and western Germany....
and up to Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
. It is particularly prolific in areas where nutrients are abundant. This has been the case off the coast of Brittany
Brittany
Brittany is a cultural and administrative region in the north-west of France. Previously a kingdom and then a duchy, Brittany was united to the Kingdom of France in 1532 as a province. Brittany has also been referred to as Less, Lesser or Little Britain...
where a high level of nitrates, from the intensive farming there, washes out to sea. The result is that large quantities of Ulva lactuca are washed up on beaches, where their decay produces methane, hydrogen sulphide, and other gases.
Certain environmental conditions can lead to the algae spreading over large areas. In August 2009, unprecedented levels of the algae washed up on the beaches of Brittany
Brittany
Brittany is a cultural and administrative region in the north-west of France. Previously a kingdom and then a duchy, Brittany was united to the Kingdom of France in 1532 as a province. Brittany has also been referred to as Less, Lesser or Little Britain...
, France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, causing a major public health scare as it decomposed. The rotting thalli produced large quantities of hydrogen sulphide, a toxic gas. In one incident near Saint-Michel-en-Grève
Saint-Michel-en-Grève
Saint-Michel-en-Grève is a commune in the Côtes-d'Armor department in Bretagne in northwestern France.In 2009 vast quantities of Ulva lactuca washed up on the beach at Saint Michel causing the deaths of a horse and cleanup crew truck driver.-Population:...
, a horse rider lost consciousness and his horse died after breathing the seaweed fumes. Environmentalists blamed the phenomenon on excessive use fertilizers and the excretion of nitrates by pig and poultry farmers. In a separate incident at the same beach, a truck driver and several schoolchildren died after taking part in the cleanup without protection.
Life history
The sporangial and gametangial thalli are morphologically alike. The diploid adult plant produces haploid spores by meiosisMeiosis
Meiosis is a special type of cell division necessary for sexual reproduction. The cells produced by meiosis are gametes or spores. The animals' gametes are called sperm and egg cells....
, these settle and grow to form haploid male and female plants similar to the diploid plants. When these haploid plants release gametes they unite to produce the zygote
Zygote
A zygote , or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo...
which germinates, and grows to produce the diploid plant.
Uses
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
in soups and salads.
Further reading
- Hayden, H.S., Blomster, J., Maggs, C.A., Silva, P.C., Stanhope, M.J. and Waaland, J.R. (2003) "Linnaeus was right all along: Ulva and Enteromorpha are not distinct genera" European Journal of Phycology 38: pp. 277–294, doi: 10.1080/1364253031000136321
External links
- Ulva lactuca, AlgaeBaseAlgaeBaseAlgaeBase is a global species database of information on all groups of algae, as well as one group of flowering plants, the sea-grasses.AlgaeBase evolved from Michael Guiry's seaweed website, and has grown into a database of algae from throughout the world, and in freshwater, terrestrial, and...
entry - Ulva lactuca, University of Rhode IslandUniversity of Rhode IslandThe University of Rhode Island is the principal public research university in the U.S. state of Rhode Island. Its main campus is located in Kingston. Additional campuses include the Feinstein Campus in Providence, the Narragansett Bay Campus in Narragansett, and the W. Alton Jones Campus in West...