Sea Lettuce

Common name: Sea Lettuce

Authors: Nathan Troost and Jacob Lake

Scientific name: Ulva lactuca

Size: The average size of the thallus is 16″ across though smaller specimens are common.

Identifying features: U. lactuca is an edible green algae that is widely distributed around the world. Despite looking like lettuce it isn’t actually a lettuce.  It is only two cells thick and is attached to substrate by a disc shaped holdfast.  

Cool facts: This seaweed is eaten by humans as well as many other animals such as manatees and sea slugs.  It can often grow profusely in areas with high nutrient levels.  After the bloom the seaweed may get washed up on beaches where it decays and can produce many toxic gases such as hydrogen sulphide.  The gases from decomposing Sea Lettuce has been attributed to some animal deaths in France.