Ulva lactuca Linnaeus
Common names: Sea Lettuce. Glasán (Irish).
Description: Thallus sheet-like, light green, rather delicate thd translucent, to 250 mm long. Persists throughout the year.
Habitat: on rock and in lower-shore rock pools, and in the shallow subtidal.
Distribution: Common and widely distributed.
Key characteristics: light green colour and translucent thallus; however, this and other species of Ulva in the NE Atlantic require expert identification, and even then there is much dispute as to the status of the various species that have been reported including U. rigida, U. gigantea, U. scandinavica, and U. armoricana.
Usage: Brent Geese (Light-bellied Brent below at Silver Strand, near Galway) eat Ulva at low tide.
Photographs © M.D. Guiry