Ulva intestinalis
A tubular green alga with worldwide distribution and isomorphic generations.
Ulva intestinalis is a green alga belonging to the family Ulvaceae. Its common names include sea lettuce, green bait weed, gutweed, and grass kelp. Prior to genetic reclassification in the early 2000s, the tubular species of the sea lettuce genus Ulva were grouped under the genus Enteromorpha.
This species is found across much of the world. In the Pacific Ocean, it occurs in the Bering Sea near Alaska, the Aleutian Islands, Puget Sound, Japan, Korea, Mexico, the Philippines, Russia, and New Zealand. In the Atlantic, its range includes the Azores, the Baltic Sea, the Mediterranean Sea, and northern European countries such as Ireland, Belgium, Denmark, Norway, and Poland.
The fronds are branched and completely tubular, widening toward the middle of the thallus, and can reach 15 cm or more in length. The cells are irregularly arranged, and each contains a hood-shaped chloroplast positioned to one side, usually with a single pyrenoid. Overall, the alga grows 10–30 cm long and 6–18 mm wide, with rounded tips at the ends of the fronds.
This alga can reproduce at any time of year. Its life cycle involves alternation of generations, with both the gametophyte and sporophyte stages being isomorphic—that is, identical in appearance. Some references treat Ulva intestinalis as two subspecies: ssp. intestinalis (L.) Link and ssp. compressa (L.) Link.
In other languages, it is known as Lineáil ghorm (Irish), tarm-rørhinde (Danish), echt darmwier (Dutch), entéromorphe (French), Darmtang or gemeiner Darmtang (German), tarmgrønske (Norwegian), sałata, taśma, or watka (Polish), tarmalg (Swedish), สาหร่ายไส้ไก่ (Thai), and erva-patinha (Portuguese).
Quick Facts
- Genus
- Ulva
- Species
- intestinalis
Facts from the source article.
Lore & Background
The branched fronds of Ulva intestinalis are completely tubular and expand in width to mid-thallus, reaching 15 cm long or more. The cells are irregularly arranged and the chloroplast is hood-shaped and placed to one side, generally with only one pyrenoid. The fronds have rounded tips. This alga may be reproductive at all times of the year, and has a life-cycle with alternation of generations, in which the gametophyte and sporophyte are isomorphic, having identical morphology. In some references the species is treated as two subspecies: ssp. intestinalis and ssp. compressa.
Reader's Guide
Ulva intestinalis is notable for its reclassification history: until genetic work completed in the early 2000s, tubular members of the sea lettuce genus Ulva were placed in the genus Enteromorpha. This species has a generally world-wide distribution, documented in the Pacific Ocean (Bering Sea near Alaska, Aleutian Islands, Puget Sound, Japan, Korea, Mexico, the Philippines, Russia, and New Zealand) and the Atlantic Ocean (Azores, Baltic Sea, Mediterranean Sea, and northern European countries such as Ireland, Belgium, Denmark, Norway, and Poland). Its common names include sea lettuce, green bait weed, gutweed, and grass kelp. The alga is known in multiple languages, including Irish (Lineáil ghorm), Danish (tarm-rørhinde), Dutch (echt darmwier), French (entéromorphe), German (Darmtang, gemeiner Darmtang), Norwegian (tarmgrønske), Polish (sałata, taśma, watka), Swedish (tarmalg), Thai (สาหร่ายไส้ไก่), and Portuguese (erva-patinha). Its significance lies in its widespread occurrence and the taxonomic clarification that resolved its placement within Ulva.
Did You Know?
- Until genetic work in the early 2000s, tubular members of Ulva were placed in the genus Enteromorpha.
- The species has a life-cycle with alternation of generations, with isomorphic gametophyte and sporophyte.
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