Sea Lettuce     Ulva lactuca



Looking like some sort of green, goopy stuff that washed onto this rock, Sea Lettuce is really a marine plant.  It is a very common intertidal plant growing from mean low-tide level to around a plus two feet in our area. It ranges from Alaska to Chile as well as in other parts of the world. The blade can grow up to a foot long during the summer. It dies away as fall approaches leaving a perennial hold-fast from which another blade grows next season.


In other parts of the world the blade is eaten in salads, soups, and other dishes.


Like most plants, Sea Lettuce contains chlorophyll which captures the energy from sun light turning it into food that the cells of the plant can use in a variety of ways. It is only two cells thick so that the green from the chlorophyll shows through.


Sea Lettuce is a member of the class of plants known as Green Algae.   Other kinds of algae also occur in the intertidal zone.  They are commonly called Red and Brown Algae.  


Sea Lettuce does not appear to have any major predators although small marine snails probably eat it when it is small.  However one fish does feed on it.  A fairly common, shallow water fish called the Buffalo Sculpin eats Sea Lettuce blades in addition to animal prey.


During the summer, parts of Boston Harbor cove can be covered in this species.  It can get so thick that masses of it can choke the shallow water area. When it dies the smell of hydrogen sulfide (rotten egg smell) will fill the air.