It may be difficult to see typical animal features on the Sea Lemon and often they are mistaken for plants or inanimate marine objects by laypeople. They belong to a larger classification of animals called Nudibranches, which are soft-bodied marine mollusk related to snails, clams and octopuses. They are usually small animals, measuring between four and ten inches in length (10 to 25 cm). As their name suggests, Sea Lemons are typically pale yellow to orange and look like a flattened worm. The two “horns” on the side of their heads are called rhinophores and are used to help the animal “smell” food underwater. They feed mostly on sponges, using a rough tongue called a radula to file the sponge off the rocks they encrust. They breathe through a set of puffy gills on their back that appear like feathery rosettes. Sea Lemons produce a fruity smell which is thought to be unappealing to predators.
Like all nudibranches, Sea Lemons are hermaphrodites, meaning they can produce both sperm and eggs. Between November and March, they will lay their eggs in ribbon-like masses that can contain up to two million babies. Despite these numbers, less than one percent of the eggs will hatch and most are eaten by other marine animals.
The Sea Lemon is a commonly found in intertidal areas from Alaska to Baja California.