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Sea Lemon
Mollusc
Sea Lemon
Archidoris pseudoargus (Rapp, 1827)
WoRMS AphialID
138763
Sample IDs
HMSC174-01969
Collected
Saint Andrews NB, hand collection off wharf.
Distinguishing Features
• Head: relatively small with blunt, inconspicuous oral tentacles on either side of the mouth. One pair of conical rhinophores with up to 30 sensory lamellae.
• Body: typically a mottled yellow-orange, but varies to green, brown, or pink. Dorsally the body is covered in small tubercles of two sizes, giving a warty appearance.
• Gills: a posterior ring of 8-9 feathery, tripinnate gills, quickly retracted when disturbed.
• Size: large, to 120 mm (rarely to 200 mm).
Habitat
Low intertidal to 300 m, on rocky shores, under rocks, on sponges they feed on such as the locally common breadcrumb sponge, Halichondria panicea.
Geographic Range
Native to the Northeast Atlantic with now-established populations in the Gulf of Maine and outer Bay of Fundy.
Fun Fact
When disturbed, sea lemons produce a strong, lemony odour and acidic taste to deter predators. Fish have even been seen spitting them out! Their primary diet consists of sponges, and they lie huge, yellow ribbons of eggs. These large nudibranchs are considered an invasive species on our coast. They were introduced from Europe by shipping and first discovered in the Gulf of Maine in 2017.
Barcode Distribution
Amphi-Atlantic BIN matching specimens from Europe.
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