is a loosely-applied common name
for a group of medium-sized to large shell-less colorful sea slugs
, specifically dorid nudibranchs
in the taxonomic family Dorididae
and other closely related families. These are marine opisthobranch gastropod mollusks
One fine example is the Pacific sea lemon or speckled sea lemon, Peltodoris nobilis, which occurs along the coast of British Columbia to Baja California in low-tide waters to a depth of about 200 m. The Monterey sea lemon is Archidoris monteryensis and the mottled pale sea lemon is Anisodoris lentiginosa.
The common name sea lemon probably comes from these animal's visual similarity to a lemon based on such qualities as the roughened skin, the oval form when seen from above, and the common but not inevitable orange to pale yellow coloration.
Interestingly enough, the species Peltodoris nobilis gives off a strong fruity citrus smell when handled, adding to its resemblance to a lemon.
These dorid nudibranchs can be large (up to 20 cm
), rather flattened, and oval in shape when seen from above. They have two hornlike projections (rhinophores
) on the head, and a rosette-like tuft of gills on the back of the animal. The mantle is sometimes sprinkled with black dots, and it is covered in small bumps, which are called tubercles
Sea lemons feed on sponges
and other sessile
animals or even on dead organic matter. They lay ribbons of white or yellow eggs.
Taxonomically the Dorididae is a family of several genera, the dorids
named after the mythological ancient Greek sea nymph Doris
. (See Ovidius
Genera within the family Dorididae