Polycera atra, common name orange-spike polycera or sorcerer's sea slug, is a species of sea slug, a nudibranch, a marine gastropod mollusk in the family Polyceridae.

This species of polycerid nudibranch was described from California.

[2] The body of Polycera atra is translucent white with longitudinal black lines interspersed with rows of raised yellow spots.

The oral veil has 4-8 tapering yellow-tipped papillae.

[3] Polycera atra feeds on the bryozoan Bugula.