Family
Dorididae
Doris odhneri. Photo: (c) Chloe and Trevor Van Loon, some rights reserved (CC BY)
Sea lemon is a loosely applied common name for a group of medium-sized to large shell-less colorful sea slugs or nudibranchs, specifically dorid nudibranchs in the taxonomic family Dorididae and other closely related families. These are marine gastropod mollusks.