Tambja is a genus of colorful sea slugs, dorid nudibranchs, shell-less marine gastropod mollusks in the family Polyceridae.

[2] These nudibranchs feed on bryozoans.

They have a radula which bears a rachidian tooth whose upper margin is either smooth or notched; the lateral tooth has two crowns, and the other teeth are so flat as to resemble plates.

[3] Species in the genus Tambja include:[4] The nominal species Tambja amakusana Baba, 1987, T. mediterranea Domínguez, Pola & Ramón, 2015,[9] and T. oliva Meyer, 1977 have been placed in the new genus Martadoris.

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