Appearance
The original description reads: Doris corpore elongato, levissimo, caeruleo; dorso tribus lineis longitudinalibus notato, duobus lateralibus aurantiacis, media albida. - Longit. 4 lin.
In 1841 Cantraine expanded on this and gave an illustration.
Felimare tricolor has a blue body with a yellow-orange line running along the edge of the mantle. There is a single central white-yellow line along the midline of the mantle and paler blue diffuse patches between this line and the sides. The gills are dark blue with a single white line along the midline which becomes more prominent at the tip of each gill. The rhinophores are dark blue with a paler tip but with no yellow or white markings. There is some variation in colour between individuals and regions. The development of the colour pattern is described by Ortea et al.